The invention discloses a maintenance device for an indoor track robot of a substation and a working method thereof. The maintenance device includes a fixing track, a lifting track, a ball screw device, guide rail sliding block devices, an electric push rod and a control unit; two parallel guide rail sliding block devices are arranged on the lifting track, and both include a linear guide rail anda sliding block arranged on the linear guide rail; one end of the lifting track is provided with the electric push rod which moves in the longitudinal direction, and the other end of the lifting trackis provided with a position label and a mechanical limiting block; the ball screw device is arranged between the two guide rail sliding block devices, and the ball screw device drives the lifting track through a motor to move in the vertical direction. The control unit controls the motor to move, so that the lifting track and the fixing track fit or are separated; therefore, it is achieved that the robot which moves to the lifting track can be separated from a routing inspection track to a target position.