Friction stir welding (FSW) is a new kind of solidphase welding technology. FSW is widely used in welding of the lightweight alloys such as aluminum alloy plate because of it particular advantages. FSW system based on hydraulic servo technology was analyzed and the mathematical model of the position hydraulic servo control system was deduced. After the control system model was built in the MATLAB/Simulink module, the system was simulated by using fuzzyPID control method and PID control method. By analyzing the simulation results, the following results are achieved: both of the fuzzyPID and PID control method are effective in controlling the position of the spindle hydraulic servo system. The fuzzyPID control method works better than the PID control method in response time, control accuracy as well as antiinterference ability. The results of corresponding experiment show that the fuzzyPID control method is effective.