Recently, the performance of the DSP and FPGA is developed remarkably. So, fully digital control is enabled in switch mode power supplies. However, in many cases, the control system is built by very complicatedly and very difficult theories such as the adaptive control. Furthermore, in most popular PID control, its design method of the parameters is not clear, so derivation of the optimal parameters is very difficult. This paper proposes the interesting control technique which is cancelled the transfer function of the converter by using pole-zero-cancellation method. This technique is very simple and easy to stability design.