diff --git a/src/i18n/locales/en.json b/src/i18n/locales/en.json
index dc94ba7..61224f8 100644
--- a/src/i18n/locales/en.json
+++ b/src/i18n/locales/en.json
@@ -501,9 +501,9 @@
     "gemini_cli_oauth_title": "Gemini CLI OAuth",
     "gemini_cli_oauth_button": "Start Gemini CLI Login",
     "gemini_cli_oauth_hint": "Login to Google Gemini CLI service through OAuth flow, automatically obtain and save authentication files.",
-    "gemini_cli_project_id_label": "Google Cloud Project ID:",
-    "gemini_cli_project_id_placeholder": "Enter Google Cloud Project ID",
-    "gemini_cli_project_id_hint": "Project ID is required for Gemini CLI OAuth.",
+    "gemini_cli_project_id_label": "Google Cloud Project ID (Optional):",
+    "gemini_cli_project_id_placeholder": "Leave blank to auto-select first available project",
+    "gemini_cli_project_id_hint": "Optional. If not provided, the system will automatically select the first available project from your account.",
     "gemini_cli_project_id_required": "Please enter a Google Cloud project ID.",
     "gemini_cli_oauth_url_label": "Authorization URL:",
     "gemini_cli_open_link": "Open Link",
diff --git a/src/i18n/locales/zh-CN.json b/src/i18n/locales/zh-CN.json
index 84ad6d8..b84e8d0 100644
--- a/src/i18n/locales/zh-CN.json
+++ b/src/i18n/locales/zh-CN.json
@@ -501,9 +501,9 @@
     "gemini_cli_oauth_title": "Gemini CLI OAuth",
     "gemini_cli_oauth_button": "开始 Gemini CLI 登录",
     "gemini_cli_oauth_hint": "通过 OAuth 流程登录 Google Gemini CLI 服务，自动获取并保存认证文件。",
-    "gemini_cli_project_id_label": "Google Cloud 项目 ID:",
-    "gemini_cli_project_id_placeholder": "输入 Google Cloud 项目 ID",
-    "gemini_cli_project_id_hint": "请填写项目 ID，用于 Gemini CLI OAuth 登录。",
+    "gemini_cli_project_id_label": "Google Cloud 项目 ID (可选):",
+    "gemini_cli_project_id_placeholder": "留空将自动选择第一个可用项目",
+    "gemini_cli_project_id_hint": "可选填写项目 ID。如不填写，系统将自动选择您账号下的第一个可用项目。",
     "gemini_cli_project_id_required": "请填写 Google Cloud 项目 ID。",
     "gemini_cli_oauth_url_label": "授权链接:",
     "gemini_cli_open_link": "打开链接",
diff --git a/src/pages/OAuthPage.tsx b/src/pages/OAuthPage.tsx
index 9e35a58..124d336 100644
--- a/src/pages/OAuthPage.tsx
+++ b/src/pages/OAuthPage.tsx
@@ -131,12 +131,7 @@ export function OAuthPage() {
 
   const startAuth = async (provider: OAuthProvider) => {
     const projectId = provider === 'gemini-cli' ? (states[provider]?.projectId || '').trim() : undefined;
-    if (provider === 'gemini-cli' && !projectId) {
-      const message = t('auth_login.gemini_cli_project_id_required');
-      updateProviderState(provider, { projectIdError: message });
-      showNotification(message, 'warning');
-      return;
-    }
+    // 项目 ID 现在是可选的，如果不输入将自动选择第一个可用项目
     if (provider === 'gemini-cli') {
       updateProviderState(provider, { projectIdError: undefined });
     }
@@ -151,7 +146,7 @@ export function OAuthPage() {
     try {
       const res = await oauthApi.startAuth(
         provider,
-        provider === 'gemini-cli' ? { projectId: projectId! } : undefined
+        provider === 'gemini-cli' ? { projectId: projectId || undefined } : undefined
       );
       updateProviderState(provider, { url: res.url, state: res.state, status: 'waiting', polling: true });
       if (res.state) {