Abstract: Based on the existing control strategy and experimental result of the digital current following controlling Buck DC-DC converter, the reasons why load chances the dynamic response time is long and the output voltage can not recover expected value are analyzed, and an improved control strategy is proposed. Based on the existing control strategy, the improved control strategy adds the detection of the load changes process. If the load changes occur, the new control strategy is switched automatically. According to the shock loading and unloading, the mathematical models of the changes are established respectively, the corresponding control strategies are designed, and the hardware test results are given. The experimental results show that the proposed control strategy is correct and feasible in steady state control and dynamic process control. On the basis of ensuring the output voltage accuracy in steady state, the dynamic performance of the converter is improved.