With the continuous expansion of DC / DC converter in practical application the requirements for input fluctuation response speed and stability are higher and higher while the traditional PID control algorithm cannot obtain ideal control effect in complex converter control system. Taking Buck converter as the research object an improved active disturbance rejection control ADRC strategy is proposed. Based on the traditional linear ADRC a generalized mathematical analysis is carried out and a self-defined zero point is introduced into the transfer function. At the same time for the interference of input channel and measurement the measurement filter is designed and the second-order ADRC is designed. Finally a hardware test platform with DSP28377 as the controller is built the dynamic performance of traditional PI control and improved ADRC under interference is compared and analyzed and the feasibility of the improved ADRC scheme is verified. The proposed improved control strategy not only overcomes the shortcomings of traditional PID control but also retains its simple structure. The experimental results show that compared with the traditional PID algorithm the adjustment time is reduced by 125 μs and the overshoot is less than 0. 8% during the loading process. During the load shedding process the adjustment time is reduced by 165 μs and the overshoot is reduced by 2. 8%. It can be concluded that the improved ADRC strategy not only has the characteristics of high speed and high precision but also has better robustness and anti-disturbance performance.