A set of piston nut lock special machine was designed to solve the lock nut’s problem in the end of the piston rod in shock absorber. The mechanical composition and the operating principle were introduced.Then the principle diagrams of the hydraulic pressure system and the air pressure system were drawn. The hardware wiring diagram and the sequence control function were given. It is proved that the productivity is enhanced greatly, it has the characteristics of simple structure, stable work and good locking quality.