An installing tool for a piston rod and a snap ring comprises a working table, a bench drill, a snap ring installing base and a piston rod supporting base. The bench drill comprises a rack, a bench drill rod and a motor, the rack is fixedly connected to the working table, the bench drill rod is connected into the rack, the motor is arranged above the rack, and an output shaft of the motor is connected to the bench drill rod. The snap ring installing base is arranged on the working table and located below the bench drill rod. The section of the snap ring installing base is in a U shape, a baffle is arranged at one end of the snap ring installing base, and a snap ring is arranged in a U-shaped cavity of the snap ring installing base and fixed through the baffle. The piston rod supporting base is connected to the working table through a sliding rail structure and used for supporting the piston rod, and the center of the piston rod supporting base and the center of the snap ring installing base are located on the same straight line. Operation is easy and convenient, and working efficiency is improved.