I've tried this, It works! max_buffer_size
default value is 100 M.
import tornado.httpserver
app = tornado.web.Application([
(r'/upload/', UploadFileHandler),
])
server = tornado.httpserver.HTTPServer(app, max_buffer_size=10485760000) # 10G
server.listen(8888)
tornado.ioloop.IOLoop.instance().start()