In particular situation,large heavyduty servo cylinder is often horizontal articulated installed and outputs curve force. In order to improve the servo cylinder frequency response characteristics, stabilize the work and extend its service life, a servo cylinder is hinged with the support mechanism of a small hydraulic cylinder, which is equipped with control system, in the bottom. When the servo cylinder is working, the external control system must ensure that both the pressure and the location meet requirements of the system, to get precise control. For the required conditions, the servo control system of a double closedloop independent PID based on pressureposition was designed. Through the analysis of double closedloop control system of pressureposition, the mathematical model of the system was deduced and its stability was analyzed by using Lyapunov’s second method,to verify its rationality and effectiveness. Above all, the feasibility and reliability of the control system were proved by using the cosimulation of AMESim and MATLAB, thus precise control for synchronization of the pressure and position was achieved.