Because of the nonlinear of electrohydraulic servo system, the conventional modeling methods cannot be accurately modeled which results that it is difficult to improve the control accuracy and stability. A nonlinear mathematical model according to a closed loop electrohydraulic servo control system was established, then the model was established the accurate feedback of linear modeling feedback based on differential geometry method and linear quadratic optimal control method was used to calculate the optimal control law of the system, the optimal control was implemented based on the model for the marine mechanical property testing platform. The results show that the combination of exact linearization feedback and optimal control make that the system of fast response and control accuracy are superior to conventional PID control algorithm. 