diff --git a/modules/io.github.xenfork.freeworld.client/src/main/java/io/github/xenfork/freeworld/client/Freeworld.java b/modules/io.github.xenfork.freeworld.client/src/main/java/io/github/xenfork/freeworld/client/Freeworld.java
index ecf62b4..2305ab1 100644
--- a/modules/io.github.xenfork.freeworld.client/src/main/java/io/github/xenfork/freeworld/client/Freeworld.java
+++ b/modules/io.github.xenfork.freeworld.client/src/main/java/io/github/xenfork/freeworld/client/Freeworld.java
@@ -15,9 +15,11 @@
 import io.github.xenfork.freeworld.client.render.gl.GLStateMgr;
 import io.github.xenfork.freeworld.client.render.world.HitResult;
 import io.github.xenfork.freeworld.core.registry.BuiltinRegistries;
+import io.github.xenfork.freeworld.util.Direction;
 import io.github.xenfork.freeworld.util.Logging;
 import io.github.xenfork.freeworld.util.Timer;
 import io.github.xenfork.freeworld.world.World;
+import io.github.xenfork.freeworld.world.block.BlockType;
 import io.github.xenfork.freeworld.world.block.BlockTypes;
 import io.github.xenfork.freeworld.world.entity.Entity;
 import io.github.xenfork.freeworld.world.entity.EntityTypes;
@@ -64,6 +66,8 @@ public final class Freeworld implements AutoCloseable {
     private World world;
     private Entity player;
     private int blockDestroyTimer = 0;
+    private int blockPlaceTimer = 0;
+    private int selectBlock = 0;
 
     private Freeworld() {
         this.glfw = GLFW.INSTANCE;
@@ -132,6 +136,13 @@ private void onKey(int key, int scancode, int action, int mods) {
                     }
                 }
             }
+            case GLFW.PRESS -> {
+                switch (key) {
+                    case GLFW.KEY_1 -> selectBlock = 0;
+                    case GLFW.KEY_2 -> selectBlock = 1;
+                    case GLFW.KEY_3 -> selectBlock = 2;
+                }
+            }
         }
     }
 
@@ -187,7 +198,30 @@ private void tick() {
                 blockDestroyTimer = 0;
             }
         }
+        if (blockPlaceTimer >= 3) {
+            final HitResult hitResult = gameRenderer.hitResult();
+            if (!hitResult.missed() &&
+                glfw.getMouseButton(window, GLFW.MOUSE_BUTTON_RIGHT) == GLFW.PRESS) {
+                final Direction face = hitResult.face();
+                final BlockType type = switch (selectBlock) {
+                    case 0 -> BlockTypes.STONE;
+                    case 1 -> BlockTypes.DIRT;
+                    case 2 -> BlockTypes.GRASS_BLOCK;
+                    default -> BlockTypes.AIR;
+                };
+                if (!type.air()) {
+                    world.setBlockType(
+                        hitResult.x() + face.axisX(),
+                        hitResult.y() + face.axisY(),
+                        hitResult.z() + face.axisZ(),
+                        type
+                    );
+                }
+                blockPlaceTimer = 0;
+            }
+        }
         blockDestroyTimer++;
+        blockPlaceTimer++;
     }
 
     private void initGL() {
diff --git a/modules/io.github.xenfork.freeworld.client/src/main/java/io/github/xenfork/freeworld/client/render/GameRenderer.java b/modules/io.github.xenfork.freeworld.client/src/main/java/io/github/xenfork/freeworld/client/render/GameRenderer.java
index 26d28c4..b2e5448 100644
--- a/modules/io.github.xenfork.freeworld.client/src/main/java/io/github/xenfork/freeworld/client/render/GameRenderer.java
+++ b/modules/io.github.xenfork.freeworld.client/src/main/java/io/github/xenfork/freeworld/client/render/GameRenderer.java
@@ -24,6 +24,7 @@
 import io.github.xenfork.freeworld.client.render.world.WorldRenderer;
 import io.github.xenfork.freeworld.core.Identifier;
 import io.github.xenfork.freeworld.core.math.AABBox;
+import io.github.xenfork.freeworld.util.Direction;
 import io.github.xenfork.freeworld.util.Logging;
 import org.joml.Matrix4f;
 import org.slf4j.Logger;
@@ -52,7 +53,7 @@ public final class GameRenderer implements GLResource {
     private BlockRenderer blockRenderer;
     private WorldRenderer worldRenderer;
     private Tessellator tessellator;
-    private HitResult hitResult = new HitResult(null, 0, 0, 0, true);
+    private HitResult hitResult = new HitResult(true, null, 0, 0, 0, Direction.SOUTH);
 
     public GameRenderer(Freeworld client) {
         this.client = client;
diff --git a/modules/io.github.xenfork.freeworld.client/src/main/java/io/github/xenfork/freeworld/client/render/world/HitResult.java b/modules/io.github.xenfork.freeworld.client/src/main/java/io/github/xenfork/freeworld/client/render/world/HitResult.java
index fd8c3af..18f4b35 100644
--- a/modules/io.github.xenfork.freeworld.client/src/main/java/io/github/xenfork/freeworld/client/render/world/HitResult.java
+++ b/modules/io.github.xenfork.freeworld.client/src/main/java/io/github/xenfork/freeworld/client/render/world/HitResult.java
@@ -10,6 +10,7 @@
 
 package io.github.xenfork.freeworld.client.render.world;
 
+import io.github.xenfork.freeworld.util.Direction;
 import io.github.xenfork.freeworld.world.block.BlockType;
 
 /**
@@ -17,10 +18,11 @@
  * @since 0.1.0
  */
 public record HitResult(
+    boolean missed,
     BlockType blockType,
     int x,
     int y,
     int z,
-    boolean missed
+    Direction face
 ) {
 }
diff --git a/modules/io.github.xenfork.freeworld.client/src/main/java/io/github/xenfork/freeworld/client/render/world/WorldRenderer.java b/modules/io.github.xenfork.freeworld.client/src/main/java/io/github/xenfork/freeworld/client/render/world/WorldRenderer.java
index 3b21824..aedb831 100644
--- a/modules/io.github.xenfork.freeworld.client/src/main/java/io/github/xenfork/freeworld/client/render/world/WorldRenderer.java
+++ b/modules/io.github.xenfork.freeworld.client/src/main/java/io/github/xenfork/freeworld/client/render/world/WorldRenderer.java
@@ -145,6 +145,7 @@ public HitResult selectBlock() {
         int nearestX = 0;
         int nearestY = 0;
         int nearestZ = 0;
+        Direction face = Direction.SOUTH;
 
         final float radius = 5.0f;
         final float radiusSquared = radius * radius;
@@ -187,13 +188,173 @@ public HitResult selectBlock() {
                             nearestX = x;
                             nearestY = y;
                             nearestZ = z;
+                            face = detectFace(
+                                ox,
+                                oy,
+                                oz,
+                                frustumRayDir.x(),
+                                frustumRayDir.y(),
+                                frustumRayDir.z(),
+                                box
+                            );
                         }
                     }
                 }
             }
         }
 
-        return new HitResult(nearestBlock, nearestX, nearestY, nearestZ, nearestBlock == null);
+        // TODO: 2024/4/12 squid233: detect face
+        return new HitResult(nearestBlock == null, nearestBlock, nearestX, nearestY, nearestZ, face);
+    }
+
+    private Direction detectFace(
+        double originX,
+        double originY,
+        double originZ,
+        double dirX,
+        double dirY,
+        double dirZ,
+        AABBox box
+    ) {
+        double t = -1.0;
+        Direction direction = Direction.SOUTH;
+        for (Direction dir : Direction.LIST) {
+            final double v = rayFace(dir, originX, originY, originZ, dirX, dirY, dirZ, box);
+            if (v > t) {
+                t = v;
+                direction = dir;
+            }
+        }
+        return direction;
+    }
+
+    private double rayFace(
+        Direction direction,
+        double originX,
+        double originY,
+        double originZ,
+        double dirX,
+        double dirY,
+        double dirZ,
+        AABBox box
+    ) {
+        final double epsilon = 0.001;
+        final double minX = box.minX();
+        final double minY = box.minY();
+        final double minZ = box.minZ();
+        final double maxX = box.maxX();
+        final double maxY = box.maxY();
+        final double maxZ = box.maxZ();
+        return switch (direction) {
+            case WEST -> Math.max(
+                Intersectiond.intersectRayTriangleFront(
+                    originX, originY, originZ,
+                    dirX, dirY, dirZ,
+                    minX, maxY, minZ,
+                    minX, minY, minZ,
+                    minX, minY, maxZ,
+                    epsilon
+                ),
+                Intersectiond.intersectRayTriangleFront(
+                    originX, originY, originZ,
+                    dirX, dirY, dirZ,
+                    minX, minY, maxZ,
+                    minX, maxY, maxZ,
+                    minX, maxY, minZ,
+                    epsilon
+                )
+            );
+            case EAST -> Math.max(
+                Intersectiond.intersectRayTriangleFront(
+                    originX, originY, originZ,
+                    dirX, dirY, dirZ,
+                    maxX, maxY, maxZ,
+                    maxX, minY, maxZ,
+                    maxX, minY, minZ,
+                    epsilon
+                ),
+                Intersectiond.intersectRayTriangleFront(
+                    originX, originY, originZ,
+                    dirX, dirY, dirZ,
+                    maxX, minY, minZ,
+                    maxX, maxY, minZ,
+                    maxX, maxY, maxZ,
+                    epsilon
+                )
+            );
+            case DOWN -> Math.max(
+                Intersectiond.intersectRayTriangleFront(
+                    originX, originY, originZ,
+                    dirX, dirY, dirZ,
+                    minX, minY, maxZ,
+                    minX, minY, minZ,
+                    maxX, minY, minZ,
+                    epsilon
+                ),
+                Intersectiond.intersectRayTriangleFront(
+                    originX, originY, originZ,
+                    dirX, dirY, dirZ,
+                    maxX, minY, minZ,
+                    maxX, minY, maxZ,
+                    minX, minY, maxZ,
+                    epsilon
+                )
+            );
+            case UP -> Math.max(
+                Intersectiond.intersectRayTriangleFront(
+                    originX, originY, originZ,
+                    dirX, dirY, dirZ,
+                    minX, maxY, minZ,
+                    minX, maxY, maxZ,
+                    maxX, maxY, maxZ,
+                    epsilon
+                ),
+                Intersectiond.intersectRayTriangleFront(
+                    originX, originY, originZ,
+                    dirX, dirY, dirZ,
+                    maxX, maxY, maxZ,
+                    maxX, maxY, minZ,
+                    minX, maxY, minZ,
+                    epsilon
+                )
+            );
+            case NORTH -> Math.max(
+                Intersectiond.intersectRayTriangleFront(
+                    originX, originY, originZ,
+                    dirX, dirY, dirZ,
+                    maxX, maxY, minZ,
+                    maxX, minY, minZ,
+                    minX, minY, minZ,
+                    epsilon
+                ),
+                Intersectiond.intersectRayTriangleFront(
+                    originX, originY, originZ,
+                    dirX, dirY, dirZ,
+                    minX, minY, minZ,
+                    minX, maxY, minZ,
+                    maxX, maxY, minZ,
+                    epsilon
+                )
+            );
+            case SOUTH -> Math.max(
+                Intersectiond.intersectRayTriangleFront(
+                    originX, originY, originZ,
+                    dirX, dirY, dirZ,
+                    minX, maxY, maxZ,
+                    minX, minY, maxZ,
+                    maxX, minY, maxZ,
+                    epsilon
+                ),
+                Intersectiond.intersectRayTriangleFront(
+                    originX, originY, originZ,
+                    dirX, dirY, dirZ,
+                    maxX, minY, maxZ,
+                    maxX, maxY, maxZ,
+                    minX, maxY, maxZ,
+                    epsilon
+                )
+            );
+        };
     }
 
     @Override