The utility model discloses a plunger piston assembly pulling-out force measuring auxiliary tool and belongs to the technical field of hydraulic pumps and hydraulic motors. The plunger piston assembly pulling-out force measuring auxiliary tool comprises a plunger piston wrapping body used for wrapping a plunger piston in a plunger piston assembly and a sliding shoe support disc sleeving the left side of a sliding shoe in the plunger piston assembly, a sleeve cylinder sleeves the plunger piston wrapping body in a matched manner, a clamping rod I is hinged on the left end of the sleeve cylinder, the sliding shoe support disc reaches to the right side face of the sliding shoe support disc from the left end of the plunger piston in a sleeving manner, then the sliding shoe support disc is abutted against the left side face of the sliding shoe, the left side of the sliding shoe support disc is provided with a fixed seat which is fixedly connected with the same, and a clamping rod II is hinged on the right end of the fixed seat. The tool of the utility model is simple in structure and convenient to install. When the plunger piston assembly is mounted on the tool, a corresponding plunger piston wrapping body and a corresponding sliding shoe support disc are selected according to the model of the plunger assembly, assembling operation can be completed through pins and screw bolts, the clamping rods I and II that are arranged at two ends can be clamped through a pulling force machine, the plunger piston does not need to be processed or transformed, the tool is convenient to dismount, and test efficiency is improved.