diff --git a/list.md b/list.md
index ac8b223..8bbf091 100644
--- a/list.md
+++ b/list.md
@@ -6,7 +6,7 @@
 
 - [x] `_tWinMain` - `src/source/Tetris.cpp`
 - [x] `MyRegisterClass` - `src/source/Tetris.cpp`
-- [ ] `InitInstance` - `src/source/Tetris.cpp`
+- [x] `InitInstance` - `src/source/Tetris.cpp`
 - [ ] `WndProc` - `src/source/Tetris.cpp`
 - [ ] `About` - `src/source/Tetris.cpp`
 
diff --git a/report/images/Part1/InitInstanceBefore.png b/report/images/Part1/InitInstanceBefore.png
new file mode 100644
index 0000000..e7dc555
Binary files /dev/null and b/report/images/Part1/InitInstanceBefore.png differ
diff --git a/src/source/Tetris.cpp b/src/source/Tetris.cpp
index 956f549..fb56eb4 100644
--- a/src/source/Tetris.cpp
+++ b/src/source/Tetris.cpp
@@ -71,9 +71,34 @@ ATOM MyRegisterClass(HINSTANCE hInstance)
 BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
 {
     // TODO(作业3): 创建并显示主窗口。
-    UNREFERENCED_PARAMETER(hInstance);
-    UNREFERENCED_PARAMETER(nCmdShow);
-    return FALSE;
+    
+    RECT rect = { 0, 0, GRID * nWidth, GRID * nHeight };
+    AdjustWindowRect(&rect, WS_OVERLAPPEDWINDOW, TRUE);
+
+    hInst = hInstance;
+
+    HWND hWnd = CreateWindow(
+        szWindowClass,
+        szTitle,
+        WS_OVERLAPPEDWINDOW,
+        CW_USEDEFAULT,
+        0,
+        rect.right - rect.left,
+        rect.bottom - rect.top,
+        nullptr,
+        nullptr,
+        hInstance,
+        nullptr);
+
+    if (!hWnd)
+    {
+        return FALSE;
+    }
+
+    ShowWindow(hWnd, nCmdShow);
+    UpdateWindow(hWnd);
+
+    return TRUE;
 }
 
 LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)