diff --git a/cmd/client/flags.go b/cmd/client/flags.go
index a119927fb5..0562e15da4 100644
--- a/cmd/client/flags.go
+++ b/cmd/client/flags.go
@@ -13,6 +13,7 @@ import (
 
 func RegisterAppFlag(cmd *cobra.Command) {
 	cmd.Flags().Bool(watcher.FlagFastQuery, false, "Enable the fast query mode for rpc queries")
+	cmd.Flags().Int(watcher.FlagFastQueryLru, 1000, "Set the size of LRU cache under fast-query mode")
 	cmd.Flags().Bool(rpc.FlagPersonalAPI, true, "Enable the personal_ prefixed set of APIs in the Web3 JSON-RPC spec")
 	cmd.Flags().Bool(evmtypes.FlagEnableBloomFilter, true, "Enable bloom filter for event logs")
 	cmd.Flags().Int64(filters.FlagGetLogsHeightSpan, -1, "config the block height span for get logs")
diff --git a/go.mod b/go.mod
index ee67ab0622..0089f4e82d 100644
--- a/go.mod
+++ b/go.mod
@@ -23,6 +23,7 @@ require (
 	github.com/google/uuid v1.1.1
 	github.com/gorilla/mux v1.8.0
 	github.com/gorilla/websocket v1.4.2
+	github.com/hashicorp/golang-lru v0.5.5-0.20210104140557-80c98217689d
 	github.com/jinzhu/gorm v1.9.16
 	github.com/json-iterator/go v1.1.9
 	github.com/mattn/go-colorable v0.1.7 // indirect
diff --git a/x/evm/watcher/db.go b/x/evm/watcher/db.go
index eea04c51e3..3730f7c617 100644
--- a/x/evm/watcher/db.go
+++ b/x/evm/watcher/db.go
@@ -11,6 +11,7 @@ import (
 )
 
 const FlagFastQuery = "fast-query"
+const FlagFastQueryLru = "fast-lru"
 
 type WatchStore struct {
 	db *leveldb.DB
diff --git a/x/evm/watcher/querier.go b/x/evm/watcher/querier.go
index 4039124e6e..9ce5bc28aa 100644
--- a/x/evm/watcher/querier.go
+++ b/x/evm/watcher/querier.go
@@ -6,6 +6,8 @@ import (
 	"errors"
 	"strconv"
 
+	"github.com/hashicorp/golang-lru/simplelru"
+
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/ethereum/go-ethereum/common"
 	ethtypes "github.com/ethereum/go-ethereum/core/types"
@@ -20,6 +22,7 @@ const MsgFunctionDisable = "fast query function has been disabled"
 type Querier struct {
 	store *WatchStore
 	sw    bool
+	lru   *simplelru.LRU
 }
 
 func (q Querier) enabled() bool {
@@ -31,7 +34,11 @@ func (q *Querier) Enable(sw bool) {
 }
 
 func NewQuerier() *Querier {
-	return &Querier{store: InstanceOfWatchStore(), sw: IsWatcherEnabled()}
+	lru, e := simplelru.NewLRU(GetWatchLruSize(), nil)
+	if e != nil {
+		panic(errors.New("Failed to init LRU Cause " + e.Error()))
+	}
+	return &Querier{store: InstanceOfWatchStore(), sw: IsWatcherEnabled(), lru: lru}
 }
 
 func (q Querier) GetTransactionReceipt(hash common.Hash) (*TransactionReceipt, error) {
@@ -148,16 +155,19 @@ func (q Querier) GetCodeByHash(codeHash []byte) ([]byte, error) {
 	if !q.enabled() {
 		return nil, errors.New(MsgFunctionDisable)
 	}
-	var codeInfo CodeInfo
-	info, e := q.store.Get(append(prefixCodeHash, codeHash...))
-	if e != nil {
-		return nil, e
+	cacheCode, ok := q.lru.Get(common.BytesToHash(codeHash))
+	if ok {
+		data, ok := cacheCode.([]byte)
+		if ok {
+			return data, nil
+		}
 	}
-	e = json.Unmarshal(info, &codeInfo)
+	code, e := q.store.Get(append(prefixCodeHash, codeHash...))
 	if e != nil {
 		return nil, e
 	}
-	return hex.DecodeString(codeInfo.Code)
+	q.lru.Add(common.BytesToHash(codeHash), code)
+	return code, nil
 }
 
 func (q Querier) GetLatestBlockNumber() (uint64, error) {
diff --git a/x/evm/watcher/types.go b/x/evm/watcher/types.go
index 25cfde4441..63cadba64d 100644
--- a/x/evm/watcher/types.go
+++ b/x/evm/watcher/types.go
@@ -114,18 +114,10 @@ type MsgCodeByHash struct {
 	Code string
 }
 
-func NewMsgCodeByHash(hash []byte, code []byte, height uint64) *MsgCodeByHash {
-	codeInfo := CodeInfo{
-		Height: height,
-		Code:   hexutils.BytesToHex(code),
-	}
-	jsCode, e := json.Marshal(codeInfo)
-	if e != nil {
-		return nil
-	}
+func NewMsgCodeByHash(hash []byte, code []byte) *MsgCodeByHash {
 	return &MsgCodeByHash{
 		Key:  hash,
-		Code: string(jsCode),
+		Code: string(code),
 	}
 }
 
diff --git a/x/evm/watcher/watcher.go b/x/evm/watcher/watcher.go
index 5541f2e3e2..45a76904cb 100644
--- a/x/evm/watcher/watcher.go
+++ b/x/evm/watcher/watcher.go
@@ -31,6 +31,10 @@ func IsWatcherEnabled() bool {
 	return viper.GetBool(FlagFastQuery)
 }
 
+func GetWatchLruSize() int {
+	return viper.GetInt(FlagFastQueryLru)
+}
+
 func NewWatcher() *Watcher {
 	return &Watcher{store: InstanceOfWatchStore(), sw: IsWatcherEnabled(), firstUse: true}
 }
@@ -89,7 +93,7 @@ func (w *Watcher) SaveContractCodeByHash(hash []byte, code []byte) {
 	if !w.Enabled() {
 		return
 	}
-	wMsg := NewMsgCodeByHash(hash, code, w.height)
+	wMsg := NewMsgCodeByHash(hash, code)
 	if wMsg != nil {
 		w.staleBatch = append(w.staleBatch, wMsg)
 	}
@@ -262,7 +266,7 @@ func (w *Watcher) CommitCodeHashToDb(hash []byte, code []byte) {
 	if !w.Enabled() {
 		return
 	}
-	wMsg := NewMsgCodeByHash(hash, code, w.height)
+	wMsg := NewMsgCodeByHash(hash, code)
 	if wMsg != nil {
 		w.store.Set(wMsg.GetKey(), []byte(wMsg.GetValue()))
 	}