The long cylinder piston rod is made of 45 steel, and its processing route is: forging (rolling)-blanking-tempering-straightening-machining-surface quenching, tempering-straightening-rod head welding-machining-grinding-stress relieving annealing-polishing-hard chromium plating-polishing-cleaning-assembly. Heat treatment of piston rod is a key process to ensure the internal quality and mechanical properties of piston rod. The quality of heat treatment is directly related to the life and reliability of the whole hydraulic system. If the heat treatment is improper, the piston rod will break prematurely and its parts will be damaged. In severe cases, it may cause the destruction of the whole equipment and casualties.