A method of upgrading controller cluster includes the following steps. A leader controller downloads an upgrade file of a latest version from a version server and executes upgrade in version. The leader controller sends an upgrade announcement message to region controllers and receive upgrade announcement response messages having the same type of product and different current version information from the region controllers. The leader controller records the corresponding region controllers included in the upgrade announcement response messages, sends a download start message to the recorded region controllers, and starts a local file server for the recorded region controllers.