The invention discloses a rear cabinet door positioning device for a switch cabinet. The rear cabinet door positioning device includes a moving trolley, a fixing mechanism and a lifting driving mechanism, a supporting assembly is arranged on the moving trolley, the fixing mechanism includes a fixing frame and a connecting piece for detachably connecting with the rear cabinet door of the switch cabinet, the connecting piece is arranged on the fixing frame, and the fixing frame can be arranged on the supporting assembly in a lifting mode through a sliding guiding mechanism; and the lifting driving mechanism is arranged on the supporting assembly and connected with the fixing frame to drive the fixing mechanism to ascend or descend. According to the rear cabinet door positioning device for the switch cabinet, carrying and fixing the rear cabinet door of the switch cabinet of operation and maintenance personnel can be replaced in the assembly and disassembly processes of the rear cabinet door of the switch cabinet, thus the risk that the operation and maintenance personnel lacks of physical strength and is injured possibility due to the high height and weight of the rear cabinet door when disassembling and assembling the rear cabinet door of the switch cabinet is avoided, and personal safety of the operation and maintenance personnel is guaranteed.