diff --git a/cpp/src/wrapper/knowhere/vec_impl.cpp b/cpp/src/wrapper/knowhere/vec_impl.cpp
index 7efbd54f0f..d1cc1ae4ff 100644
--- a/cpp/src/wrapper/knowhere/vec_impl.cpp
+++ b/cpp/src/wrapper/knowhere/vec_impl.cpp
@@ -134,6 +134,24 @@ IndexType VecIndexImpl::GetType() {
     return type;
 }
 
+VecIndexPtr VecIndexImpl::CopyToGpu(const int64_t &device_id, const Config &cfg) {
+    //if (auto new_type = GetGpuIndexType(type)) {
+    //    auto device_index = index_->CopyToGpu(device_id);
+    //    return std::make_shared<VecIndexImpl>(device_index, new_type);
+    //}
+    //return nullptr;
+
+    // TODO(linxj): update type
+    auto gpu_index = zilliz::knowhere::CopyCpuToGpu(index_, device_id, cfg);
+    return std::make_shared<VecIndexImpl>(gpu_index, type);
+}
+
+// TODO(linxj): rename copytocpu => copygputocpu
+VecIndexPtr VecIndexImpl::CopyToCpu(const Config &cfg) {
+    auto cpu_index = zilliz::knowhere::CopyGpuToCpu(index_, cfg);
+    return std::make_shared<VecIndexImpl>(cpu_index, type);
+}
+
 float *BFIndex::GetRawVectors() {
     auto raw_index = std::dynamic_pointer_cast<IDMAP>(index_);
     if (raw_index) { return raw_index->GetRawVectors(); }
diff --git a/cpp/src/wrapper/knowhere/vec_impl.h b/cpp/src/wrapper/knowhere/vec_impl.h
index c4a0e2ac61..5e46c16f70 100644
--- a/cpp/src/wrapper/knowhere/vec_impl.h
+++ b/cpp/src/wrapper/knowhere/vec_impl.h
@@ -25,6 +25,8 @@ class VecIndexImpl : public VecIndex {
                                    const Config &cfg,
                                    const long &nt,
                                    const float *xt) override;
+    VecIndexPtr CopyToGpu(const int64_t &device_id, const Config &cfg) override;
+    VecIndexPtr CopyToCpu(const Config &cfg) override;
     IndexType GetType() override;
     int64_t Dimension() override;
     int64_t Count() override;
diff --git a/cpp/src/wrapper/knowhere/vec_index.h b/cpp/src/wrapper/knowhere/vec_index.h
index 80c8771dda..088228386c 100644
--- a/cpp/src/wrapper/knowhere/vec_index.h
+++ b/cpp/src/wrapper/knowhere/vec_index.h
@@ -35,6 +35,9 @@ enum class IndexType {
     NSG_MIX,
 };
 
+class VecIndex;
+using VecIndexPtr = std::shared_ptr<VecIndex>;
+
 class VecIndex {
  public:
     virtual server::KnowhereError BuildAll(const long &nb,
@@ -55,6 +58,11 @@ class VecIndex {
                                          long *ids,
                                          const Config &cfg = Config()) = 0;
 
+    virtual VecIndexPtr CopyToGpu(const int64_t& device_id,
+                                  const Config &cfg = Config()) = 0;
+
+    virtual VecIndexPtr CopyToCpu(const Config &cfg = Config()) = 0;
+
     virtual IndexType GetType() = 0;
 
     virtual int64_t Dimension() = 0;
@@ -66,8 +74,6 @@ class VecIndex {
     virtual server::KnowhereError Load(const zilliz::knowhere::BinarySet &index_binary) = 0;
 };
 
-using VecIndexPtr = std::shared_ptr<VecIndex>;
-
 extern server::KnowhereError write_index(VecIndexPtr index, const std::string &location);
 
 extern VecIndexPtr read_index(const std::string &location);