Hydraulic technology is a scientific technology involving the law of liquid flow and pressure. In recent decades, hydraulic technology has developed very fast. Widely used in industry, agriculture and national defense and other departments. Such as machinery manufacturing, lifting equipment, mining machinery, construction machinery, agricultural machinery and chemical machinery; and such as warship steering gear, radar scanning equipment, tanks, artillery, aircraft, missiles and so on, all use hydraulic technology. Especially in the machine tool industry, because the use of hydraulic transmission can achieve stepless speed change, automation and frequency-tight commutation in reciprocating motion, so its application is constantly expanding and improving.