A novel robust PID design method is presented in this paper.This method gets the reasonable PID controller parameters based on min-max principle，which can guarantee the control quality when the model varies in a certain range，decrease the sensitivity to the model uncertainty and increase the robustness of the closed-loop system.Since the min-max problem is not computationally tractable，the authors address this problem by first deriving an upper bound on the robust performance objective and then translating the min-max problem into the minimization problem with the upper bound on the worst-case objective.The paper proves the robust stability of the PID design method.The simulation result of CSTR problem is given to demonstrate the effectiveness of the robust PID design method.