diff --git a/apps/api/app/api/routes/generation_preview.py b/apps/api/app/api/routes/generation_preview.py
index 3072a8f7b..db03026e9 100755
--- a/apps/api/app/api/routes/generation_preview.py
+++ b/apps/api/app/api/routes/generation_preview.py
@@ -312,7 +312,7 @@ def create_preview_generation_task(
                 project_id="",
                 asset_library_id="",
                 strategy_id=strategy_id,
-                voice_library_id="",
+                voice_library_id=request.voice_library_id,
                 template_id=request.template_id,
                 asset_ids=list(request.asset_ids),
                 title_ids=list(request.title_ids),
diff --git a/apps/api/app/schemas/generation_task.py b/apps/api/app/schemas/generation_task.py
index 8c458a9d5..3d6015276 100755
--- a/apps/api/app/schemas/generation_task.py
+++ b/apps/api/app/schemas/generation_task.py
@@ -161,6 +161,9 @@ class CreatePreviewGenerationTaskRequest(BaseModel):
     asset_ids: list[str] = Field(default_factory=list)
     title_ids: list[str] = Field(default_factory=list)
     voice_ids: list[str] = Field(default_factory=list)
+    voice_library_id: str = Field(
+        default="", description="配音素材库ID（用户上传的音频或AI配音），对应配音选择页面选择的配音素材"
+    )
     video_title: str = Field(default="", description="生成视频的标题/名称，为空则使用默认命名")
     duration: float = Field(default=0.0, ge=0, description="期望视频时长（秒），0 表示由模板决定")
     video_ratio: str = Field(default="", description="视频比例，如 16:9 / 9:16，为空使用模板默认")
diff --git a/apps/web/src/pages/generate/generate.css b/apps/web/src/pages/generate/generate.css
index 538b2914a..7bc13a098 100644
--- a/apps/web/src/pages/generate/generate.css
+++ b/apps/web/src/pages/generate/generate.css
@@ -2383,7 +2383,6 @@
   font-size: 14px;
 }
 
-
 /* ── 加载中状态 ── */
 .xx-preview-loading {
   text-align: center;
diff --git a/tests/unit/test_preview_voice_library_id.py b/tests/unit/test_preview_voice_library_id.py
new file mode 100644
index 000000000..20664c564
--- /dev/null
+++ b/tests/unit/test_preview_voice_library_id.py
@@ -0,0 +1,74 @@
+"""预览生成 voice_library_id 透传修复测试.
+
+Bug: 预览生成接口硬编码 voice_library_id=""，导致用户选择的上传音频
+在预览渲染时从未下载和混入，预览视频无声。
+
+Fix: CreatePreviewGenerationTaskRequest 增加 voice_library_id 字段，
+预览端点透传 request.voice_library_id。
+"""
+
+from __future__ import annotations
+
+import os
+import sys
+from pathlib import Path
+
+os.environ.setdefault("JWT_SECRET_KEY", "unit-test-secret-key-for-testing")
+os.environ.setdefault("DATABASE_URL", "sqlite:///test.db")
+
+sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "apps" / "api"))
+
+
+class TestPreviewVoiceLibraryIdSchema:
+    """CreatePreviewGenerationTaskRequest voice_library_id 字段测试."""
+
+    def test_default_empty_string(self):
+        """不传 voice_library_id 时默认为空字符串."""
+        from app.schemas.generation_task import CreatePreviewGenerationTaskRequest
+
+        req = CreatePreviewGenerationTaskRequest(
+            template_id="tmpl_1",
+            asset_ids=["a1"],
+        )
+        assert req.voice_library_id == ""
+
+    def test_accepts_voice_library_id(self):
+        """传入 voice_library_id 正常接收."""
+        from app.schemas.generation_task import CreatePreviewGenerationTaskRequest
+
+        req = CreatePreviewGenerationTaskRequest(
+            template_id="tmpl_1",
+            asset_ids=["a1"],
+            voice_library_id="asset_abc123",
+        )
+        assert req.voice_library_id == "asset_abc123"
+
+    def test_accepts_empty_voice_library_id(self):
+        """显式传空字符串也正常."""
+        from app.schemas.generation_task import CreatePreviewGenerationTaskRequest
+
+        req = CreatePreviewGenerationTaskRequest(
+            template_id="tmpl_1",
+            asset_ids=["a1"],
+            voice_library_id="",
+        )
+        assert req.voice_library_id == ""
+
+    def test_all_fields_including_voice_library_id(self):
+        """包含 voice_library_id 的完整请求."""
+        from app.schemas.generation_task import CreatePreviewGenerationTaskRequest
+
+        req = CreatePreviewGenerationTaskRequest(
+            template_id="tmpl_123",
+            asset_ids=["a1", "a2"],
+            title_ids=["t1"],
+            voice_ids=["v1"],
+            voice_library_id="voice_asset_456",
+            video_title="测试预览",
+            duration=30.0,
+            video_ratio="9:16",
+            bgm_config={"enabled": True, "volume": 0.5},
+        )
+        assert req.voice_library_id == "voice_asset_456"
+        assert req.asset_ids == ["a1", "a2"]
+        assert req.bgm_config["enabled"] is True