The working principle of the hydraulic press machine is a transmission method that uses liquid pressure to transmit power and control. The hydraulic device is composed of hydraulic pumps, hydraulic cylinders, hydraulic control valves and hydraulic auxiliary components. The hydraulic transmission system of the four-column hydraulic press machine consists of a power mechanism, a control mechanism, an executive mechanism, an auxiliary mechanism and a working medium. The power mechanism generally uses an oil pump as the power mechanism, which is widely used in the extrusion, bending, deep drawing of stainless steel plates and cold pressing of metal parts.