A rack server system and a method for automatically managing rack configuration information are disclosed herein. The rack server system includes a plurality of servers, plurality of fan modules, a plurality of fan control boards, and a rack management controller. The rack management controller is connected to the fan control boards, detects rack configuration information stored in the fan control boards during the operation of the rack server system, configured to update local rack configuration information stored in the rack management controller with the rack configuration information stored in the fan controllers when the local rack configuration information stored in the rack management controller is different from the rack configuration information stored in the fan control boards.