A modularized server comprises a rack, a switching mechanism, and a removable electronic device. The rack comprises a first slot and a second slot. The switching mechanism is disposed on the rack. When the removable electronic device is inserted into the first slot, the removable electronic device is operable to drive the switching mechanism to a switching position. The switching mechanism at the switching position can stop another removable electronic device different from a specific design of the removable electronic device from being inserted into the second slot.