A method for controlling a rack system including a plurality of detachable chassis, where at lease one node is disposed in the chassis and a rack management controller (RMC) is disposed in the rack system. First, at least one detecting unit connected to the RMC and the node of the chassis in the rack system is provided. Next, a status message of the chassis is detected for determining whether the status of the chassis is changed. When the status is changed, the detecting unit determines whether the node corresponding to the chassis exists in the rack system. When the node exists, the detecting unit acquires a message of a field replaceable unit (FRU) of the node. Thereafter, the detecting unit transmits the message of the FRU to the RMC. Then, the RMC determines a type of the node according to the message of the FRU.