The proportional-integral derivative (PID) controller is widely used in industry because of its simplicity and ability to solve the majority of the control problems. However, there are rare tuning rules to tackle general nonlinear processes. Therefore, a systematic tuning rule for the linear or nonlinear process models is proposed in this paper. Basically the control performance of the PID controller has Limitations due to the fixed structure and only three tuning parameters Moreover, the PID controller tuned well for the set point change process cannot work well for the disturbance rejection process. We thus develop a modified PID controller to achieve a good control performance in both the set point tracking and disturbance rejection process.