diff --git a/src/models/llm/rag/wiki_index_builder.cpp b/src/models/llm/rag/wiki_index_builder.cpp
index 0da3294..da95399 100644
--- a/src/models/llm/rag/wiki_index_builder.cpp
+++ b/src/models/llm/rag/wiki_index_builder.cpp
@@ -121,28 +121,28 @@ class WikiIndexBuilder::Impl {
 
     /***
      *
-     * @param index_f_path
+     * @param index_file_dir
      * @return
      */
-    StatusCode load_index(const std::string& index_f_path);
+    StatusCode load_index(const std::string& index_file_dir);
 
     /***
      *
-     * @param corpus_segment_path
+     * @param corpus_segment_dir
      * @return
      */
-    StatusCode load_corpus_segment(const std::string& corpus_segment_path);
+    StatusCode load_corpus_segment(const std::string& corpus_segment_dir);
 
     /***
      *
      * @param input_prompt
-     * @param referenced_corpus
+     * @param out_referenced_corpus
      * @param top_k
      * @param apply_chat_template
      * @return
      */
     StatusCode search(
-        const std::string& input_prompt, std::string& referenced_corpus, int top_k=1, bool apply_chat_template=true);
+        const std::string& input_prompt, std::string& out_referenced_corpus, int top_k=1, bool apply_chat_template=true);
 
     /***
      *
@@ -455,55 +455,97 @@ StatusCode WikiIndexBuilder::Impl::build_index(const std::string &source_wiki_co
 
 /***
  *
- * @param index_f_path
+ * @param index_file_dir
  * @return
  */
-StatusCode WikiIndexBuilder::Impl::load_index(const std::string &index_f_path) {
-    if (!FilePathUtil::is_file_exist(index_f_path)) {
-        LOG(ERROR) << fmt::format("index file: {} not exist", index_f_path);
+StatusCode WikiIndexBuilder::Impl::load_index(const std::string &index_file_dir) {
+    // gather all *.index file
+    std::vector<std::string> index_file_paths;
+    cv::glob(fmt::format("{}/*.index", index_file_dir), index_file_paths, true);
+    if (index_file_paths.empty()) {
+        LOG(ERROR) << fmt::format("no *.index index file found in {}", index_file_dir);
         return StatusCode::RAG_LOAD_INDEX_FAILED;
     }
 
-    auto* index = dynamic_cast<faiss::IndexFlatL2*>(faiss::read_index(index_f_path.c_str(), 0));
-    if (index == nullptr) {
-        LOG(ERROR) << fmt::format("load index file: {} failed", index_f_path);
-        return StatusCode::RAG_LOAD_INDEX_FAILED;
+    // sort index file
+    std::sort(index_file_paths.begin(), index_file_paths.end(), [](const std::string& path_a, const std::string& path_b) -> bool {
+        auto name_a = FilePathUtil::get_file_name(path_a);
+        auto prefix_id_a = name_a.substr(0, name_a.find(".index"));
+        prefix_id_a = prefix_id_a.substr(prefix_id_a.rfind('_') + 1);
+        auto name_b = FilePathUtil::get_file_name(path_b);
+        auto prefix_id_b = name_b.substr(0, name_b.find(".index"));
+        prefix_id_b = prefix_id_b.substr(prefix_id_b.rfind('_') + 1);
+        return std::stoi(prefix_id_a) < std::stoi(prefix_id_b);
+    });
+
+    // load and merge index file
+    std::vector<float> merged_vectors;
+    int vec_dims = 0;
+    for (auto& f_path : index_file_paths) {
+        auto* index = dynamic_cast<faiss::IndexFlatL2*>(faiss::read_index(f_path.c_str(), 0));
+        if (index == nullptr) {
+            LOG(ERROR) << fmt::format("read index file failed: {}", f_path);
+            return StatusCode::RAG_LOAD_INDEX_FAILED;
+        }
+        const float* raw_data = index->get_xb();
+        vec_dims = index->d;
+        for (size_t i = 0; i < index->ntotal * index->d; ++i) {
+            merged_vectors.push_back(raw_data[i]);
+        }
     }
-    if (_m_index == nullptr) {
-        _m_index = std::unique_ptr<faiss::IndexFlatL2>(index);
-    } else {
-        _m_index.reset(index);
+
+    if (_m_index != nullptr) {
+        _m_index.reset();
     }
+    _m_index = std::make_unique<faiss::IndexFlatL2>(vec_dims);
+    auto merged_index_ntotal = static_cast<long>(merged_vectors.size() / vec_dims);
+    _m_index->add(merged_index_ntotal, merged_vectors.data());
 
     return StatusCode::OK;
 }
 
 /***
  *
- * @param corpus_segment_path
+ * @param corpus_segment_dir
  * @return
  */
-StatusCode WikiIndexBuilder::Impl::load_corpus_segment(const std::string &corpus_segment_path) {
-    if (!FilePathUtil::is_file_exist(corpus_segment_path)) {
-        LOG(ERROR) << fmt::format("segment corpus file: {} not exist", corpus_segment_path);
-        return StatusCode::RAG_LOAD_SEGMENT_CORPUS_FAILED;
+StatusCode WikiIndexBuilder::Impl::load_corpus_segment(const std::string &corpus_segment_dir) {
+    // gather all *.jsonl file
+    std::vector<std::string> corpus_file_paths;
+    cv::glob(fmt::format("{}/*.jsonl", corpus_segment_dir), corpus_file_paths, true);
+    if (corpus_file_paths.empty()) {
+        LOG(ERROR) << fmt::format("no *.jsonl corpus file found in {}", corpus_segment_dir);
+        return StatusCode::RAG_LOAD_INDEX_FAILED;
     }
 
-    std::ifstream f_in(corpus_segment_path, std::ios::in);
-    if (!f_in.is_open() || f_in.bad()) {
-        LOG(ERROR) << fmt::format("read segment corpus file: {} failed", corpus_segment_path);
-        return StatusCode::RAG_LOAD_SEGMENT_CORPUS_FAILED;
-    }
+    // sort index file
+    std::sort(corpus_file_paths.begin(), corpus_file_paths.end(), [](const std::string& path_a, const std::string& path_b) -> bool {
+        auto name_a = FilePathUtil::get_file_name(path_a);
+        auto prefix_id_a = name_a.substr(0, name_a.find(".jsonl"));
+        prefix_id_a = prefix_id_a.substr(prefix_id_a.rfind('_') + 1);
+        auto name_b = FilePathUtil::get_file_name(path_b);
+        auto prefix_id_b = name_b.substr(0, name_b.find(".jsonl"));
+        prefix_id_b = prefix_id_b.substr(prefix_id_b.rfind('_') + 1);
+        return std::stoi(prefix_id_a) < std::stoi(prefix_id_b);
+    });
 
-    std::string line;
-    while (std::getline(f_in, line)) {
-        rapidjson::Document doc;
-        doc.Parse(line.c_str());
-        wiki_corpus_segment segment;
-        segment.id = std::to_string(doc["id"].GetInt64());
-        segment.title = doc["title"].GetString();
-        segment.text = doc["text"].GetString();
-        _m_segment_wiki_corpus.push_back(segment);
+    for (auto& corpus_segment_path : corpus_file_paths) {
+        std::ifstream f_in(corpus_segment_path, std::ios::in);
+        if (!f_in.is_open() || f_in.bad()) {
+            LOG(ERROR) << fmt::format("read segment corpus file: {} failed", corpus_segment_path);
+            return StatusCode::RAG_LOAD_SEGMENT_CORPUS_FAILED;
+        }
+
+        std::string line;
+        while (std::getline(f_in, line)) {
+            rapidjson::Document doc;
+            doc.Parse(line.c_str());
+            wiki_corpus_segment segment;
+            segment.id = std::to_string(doc["id"].GetInt64());
+            segment.title = doc["title"].GetString();
+            segment.text = doc["text"].GetString();
+            _m_segment_wiki_corpus.push_back(segment);
+        }
     }
 
     return StatusCode::OK;
@@ -512,13 +554,13 @@ StatusCode WikiIndexBuilder::Impl::load_corpus_segment(const std::string &corpus
 /***
  *
  * @param input_prompt
- * @param referenced_corpus
+ * @param out_referenced_corpus
  * @param top_k
  * @param apply_chat_template
  * @return
  */
 StatusCode WikiIndexBuilder::Impl::search(
-    const std::string &input_prompt, std::string &referenced_corpus, int top_k, bool apply_chat_template) {
+    const std::string &input_prompt, std::string &out_referenced_corpus, int top_k, bool apply_chat_template) {
     // check validation of index and corpus
     if (_m_segment_wiki_corpus.empty()) {
         LOG(ERROR) << "empty segmented corpus load them first";
@@ -549,12 +591,12 @@ StatusCode WikiIndexBuilder::Impl::search(
             auto title = _m_segment_wiki_corpus[ids[i]].title;
             auto text = _m_segment_wiki_corpus[ids[i]].text;
             auto fmt_str = fmt::format("Doc {} (Title: {}) {}\n", i + 1, title, text);
-            referenced_corpus += fmt_str;
+            out_referenced_corpus += fmt_str;
         }
 
     } else {
         for (auto& i : ids) {
-            referenced_corpus += fmt::format("title: {}\n text: {}\n",
+            out_referenced_corpus += fmt::format("title: {}\n text: {}\n",
                                              _m_segment_wiki_corpus[i].title, _m_segment_wiki_corpus[i].text);
         }
     }
@@ -1012,33 +1054,33 @@ StatusCode WikiIndexBuilder::build_index(const std::string& source_wiki_corpus_d
 
 /***
  *
- * @param index_f_path
+ * @param index_file_dir
  * @return
  */
-StatusCode WikiIndexBuilder::load_index(const std::string &index_f_path) {
-    return _m_pimpl-> load_index(index_f_path);
+StatusCode WikiIndexBuilder::load_index(const std::string &index_file_dir) {
+    return _m_pimpl-> load_index(index_file_dir);
 }
 
 /***
  *
- * @param corpus_segment_path
+ * @param corpus_segment_dir
  * @return
  */
-StatusCode WikiIndexBuilder::load_corpus_segment(const std::string &corpus_segment_path) {
-    return _m_pimpl-> load_corpus_segment(corpus_segment_path);
+StatusCode WikiIndexBuilder::load_corpus_segment(const std::string &corpus_segment_dir) {
+    return _m_pimpl-> load_corpus_segment(corpus_segment_dir);
 }
 
 /***
  *
  * @param input_prompt
- * @param referenced_corpus
+ * @param out_referenced_corpus
  * @param top_k
  * @param apply_chat_template
  * @return
  */
 StatusCode WikiIndexBuilder::search(
-    const std::string &input_prompt, std::string &referenced_corpus, int top_k, bool apply_chat_template) {
-    return _m_pimpl->search(input_prompt, referenced_corpus, top_k, apply_chat_template);
+    const std::string &input_prompt, std::string &out_referenced_corpus, int top_k, bool apply_chat_template) {
+    return _m_pimpl->search(input_prompt, out_referenced_corpus, top_k, apply_chat_template);
 }
 
 }
diff --git a/src/models/llm/rag/wiki_index_builder.h b/src/models/llm/rag/wiki_index_builder.h
index fa1f2a7..dfb1fff 100644
--- a/src/models/llm/rag/wiki_index_builder.h
+++ b/src/models/llm/rag/wiki_index_builder.h
@@ -69,30 +69,29 @@ class WikiIndexBuilder {
 
     /***
      *
-     * @param index_f_path
+     * @param index_file_dir
      * @param index
      * @return
      */
-    jinq::common::StatusCode load_index(const std::string& index_f_path);
+    jinq::common::StatusCode load_index(const std::string& index_file_dir);
 
     /***
      *
-     * @param corpus_segment_path
-     * @param segments
+     * @param corpus_segment_dir
      * @return
      */
-    jinq::common::StatusCode load_corpus_segment(const std::string& corpus_segment_path);
+    jinq::common::StatusCode load_corpus_segment(const std::string& corpus_segment_dir);
 
     /***
      *
      * @param input_prompt
-     * @param referenced_corpus
+     * @param out_referenced_corpus
      * @param top_k
      * @param aapply_chat_template
      * @return
      */
     jinq::common::StatusCode search(
-        const std::string& input_prompt, std::string& referenced_corpus, int top_k=1, bool apply_chat_template=true);
+        const std::string& input_prompt, std::string& out_referenced_corpus, int top_k=1, bool apply_chat_template=true);
 
   private:
     class Impl;