您可以在Express链中插入“全部捕获”中间件作为最后一个中间件/路由：

//configure the order of operations for request handlers:
app.configure(function(){
  app.use(express.logger('dev'));
  app.use(express.bodyParser());
  app.use(express.cookieParser());
  app.use(express.static(__dirname+'/assets'));  // try to serve static files
  app.use(app.router);                           // try to match req with a route
  app.use(redirectUnmatched);                    // redirect if nothing else sent a response
});

function redirectUnmatched(req, res) {
  res.redirect("http://www.mysite.com/");
}

...

// your routes
app.get('/', function(req, res) { ... });
...

// start listening
app.listen(3000);

我使用这样的设置来生成自定义404 Not Found页面。