diff --git a/source/api_cc/src/DeepPot.cc b/source/api_cc/src/DeepPot.cc
index d985eb4951..d0430d39d0 100644
--- a/source/api_cc/src/DeepPot.cc
+++ b/source/api_cc/src/DeepPot.cc
@@ -37,8 +37,13 @@ void DeepPot::init(const std::string& model,
               << std::endl;
     return;
   }
-  // TODO: To implement detect_backend
-  DPBackend backend = deepmd::DPBackend::TensorFlow;
+  if (model.length() >= 4 && model.substr(model.length() - 4) == ".pth") {
+        DPBackend backend = deepmd::DPBackend::PyTorch;
+    } else if (model.length() >= 3 && model.substr(model.length() - 3) == ".pb") {
+        DPBackend backend = deepmd::DPBackend::TensorFlow;
+    else {
+        throw deepmd::deepmd_exception("Unsupported model file format");
+    }
   if (deepmd::DPBackend::TensorFlow == backend) {
 #ifdef BUILD_TENSORFLOW
     dp = std::make_shared<deepmd::DeepPotTF>(model, gpu_rank, file_content);