CNC tube forming machine is a universal type of highend equipment, applied to steel tube round, square and other inner hole forming processing. In order to improve the position control precision of hydraulic system and reduce the system energy consumption, according to the working conditions of the forming machine, the design scheme of hydraulic precision control system composed of servo actuator, servo motor, grating and sensor was presented. In the scheme, servo driver was used to control the rotation of the servo motor, driving the displacement of the hydraulic cylinder of the quantitative pump, and the displacement was feed back to the servo drive by the grating,thus a closed loop control was formed to achieve the precision control effect. The design has the advantages of low cost, high processing efficiency and high precision.