diff --git a/backend/python/ace-step/backend.py b/backend/python/ace-step/backend.py
index 6b61b30cc..805dd16e1 100644
--- a/backend/python/ace-step/backend.py
+++ b/backend/python/ace-step/backend.py
@@ -47,86 +47,6 @@ MODEL_REPO_MAPPING = {
 }
 DEFAULT_REPO_ID = "ACE-Step/Ace-Step1.5"
 
-
-def _can_access_google(timeout=3.0):
-    """Check if Google is accessible (to choose HuggingFace vs ModelScope)."""
-    import socket
-    try:
-        socket.setdefaulttimeout(timeout)
-        socket.socket(socket.AF_INET, socket.SOCK_STREAM).connect(("www.google.com", 443))
-        return True
-    except (socket.timeout, socket.error, OSError):
-        return False
-
-
-def _download_from_huggingface(repo_id, local_dir, model_name):
-    """Download model from HuggingFace Hub."""
-    from huggingface_hub import snapshot_download
-    is_unified = repo_id == DEFAULT_REPO_ID or repo_id == "ACE-Step/Ace-Step1.5"
-    if is_unified:
-        download_dir = local_dir
-        print(f"[ace-step] Downloading unified repo {repo_id} to {download_dir}...", file=sys.stderr)
-    else:
-        download_dir = os.path.join(local_dir, model_name)
-        os.makedirs(download_dir, exist_ok=True)
-        print(f"[ace-step] Downloading {model_name} from {repo_id} to {download_dir}...", file=sys.stderr)
-    snapshot_download(
-        repo_id=repo_id,
-        local_dir=download_dir,
-        local_dir_use_symlinks=False,
-    )
-    return os.path.join(local_dir, model_name)
-
-
-def _download_from_modelscope(repo_id, local_dir, model_name):
-    """Download model from ModelScope."""
-    from modelscope import snapshot_download
-    is_unified = repo_id == DEFAULT_REPO_ID or repo_id == "ACE-Step/Ace-Step1.5"
-    if is_unified:
-        download_dir = local_dir
-        print(f"[ace-step] Downloading unified repo {repo_id} from ModelScope to {download_dir}...", file=sys.stderr)
-    else:
-        download_dir = os.path.join(local_dir, model_name)
-        os.makedirs(download_dir, exist_ok=True)
-        print(f"[ace-step] Downloading {model_name} from ModelScope {repo_id} to {download_dir}...", file=sys.stderr)
-    snapshot_download(
-        model_id=repo_id,
-        local_dir=download_dir,
-    )
-    return os.path.join(local_dir, model_name)
-
-
-def _ensure_model_downloaded(model_name, checkpoint_dir):
-    """
-    Ensure model is present; download from HuggingFace or ModelScope if missing.
-    model_name: e.g. "acestep-v15-turbo", "vae", "acestep-5Hz-lm-0.6B"
-    checkpoint_dir: directory that will contain model_name as a subdir.
-    Returns path to the model directory.
-    """
-    return None
-    if not model_name or not checkpoint_dir:
-        return None
-    model_path = os.path.join(checkpoint_dir, model_name)
-    if os.path.exists(model_path) and os.listdir(model_path):
-        print(f"[ace-step] Model {model_name} already at {model_path}", file=sys.stderr)
-        return model_path
-    repo_id = MODEL_REPO_MAPPING.get(model_name, DEFAULT_REPO_ID)
-    print(f"[ace-step] Model {model_name} not found, downloading...", file=sys.stderr)
-    use_hf = _can_access_google()
-    if use_hf:
-        try:
-            return _download_from_huggingface(repo_id, checkpoint_dir, model_name)
-        except Exception as e:
-            print(f"[ace-step] HuggingFace download failed: {e}, trying ModelScope", file=sys.stderr)
-            return _download_from_modelscope(repo_id, checkpoint_dir, model_name)
-    else:
-        try:
-            return _download_from_modelscope(repo_id, checkpoint_dir, model_name)
-        except Exception as e:
-            print(f"[ace-step] ModelScope download failed: {e}, trying HuggingFace", file=sys.stderr)
-            return _download_from_huggingface(repo_id, checkpoint_dir, model_name)
-
-
 def _is_float(s):
     try:
         float(s)
@@ -402,17 +322,6 @@ class BackendServicer(backend_pb2_grpc.BackendServicer):
             config_path = model_name or os.path.basename(model_dir.rstrip("/\\"))
             os.makedirs(self.checkpoint_dir, exist_ok=True)
 
-            # Auto-download DiT model and VAE if missing (same as upstream)
-            if config_path:
-                try:
-                    _ensure_model_downloaded(config_path, self.checkpoint_dir)
-                except Exception as e:
-                    print(f"[ace-step] Warning: DiT model download failed: {e}", file=sys.stderr)
-            try:
-                _ensure_model_downloaded("vae", self.checkpoint_dir)
-            except Exception as e:
-                print(f"[ace-step] Warning: VAE download failed: {e}", file=sys.stderr)
-
             self.dit_handler = AceStepHandler()
             # Patch handler so it uses our model dir instead of site-packages/checkpoints
             self.dit_handler._get_project_root = lambda: self.project_root
@@ -438,11 +347,6 @@ class BackendServicer(backend_pb2_grpc.BackendServicer):
             self.llm_handler = None
             if self.options.get("init_lm", True):
                 lm_model = self.options.get("lm_model_path", "acestep-5Hz-lm-0.6B")
-                if lm_model:
-                    try:
-                        _ensure_model_downloaded(lm_model, self.checkpoint_dir)
-                    except Exception as e:
-                        print(f"[ace-step] Warning: LM model download failed: {e}", file=sys.stderr)
                 self.llm_handler = LLMHandler()
                 lm_backend = (self.options.get("lm_backend") or "vllm").strip().lower()
                 if lm_backend not in ("vllm", "pt"):