A selection method of proportion integration differential (PID) was put forward for filter parameter of Internal model control (IMC) that made system could obtain a good robust performance. Because filter parameter of IMC PID had obvious influences to dynamic performance of closed loop system, and MonteCarlo test could prove directly the good and bad of dynamic performance of closed loop system, through MonteCarlo experiment to select filter parameter, the robustness of the system could be guaranteed. The experiment results of application of the proposed method in hydraulic automatic position control system of mill show that selected parameter can make the dynamic response of system to have a smaller overshoot and better robust performance, resulting an ideally control effect.