Abstract: A ZVZCS full-bridge converter with an improved energy recovery buffer circuit for passive clamp circuit, effectively realize the ZVS of the fore-arm switch tube and the ZCS of the hysteresis switch. Simultaneously, it can greatly reduce the rectifier diode voltage stress to achieve secondary rectifier diode and freewheeling diode zero voltage switch to reduce the diode reverse recovery losses and parasitic oscillation. In this paper, the working principle of each mode and the condition of realizing soft switch are analyzed, the main parameters are designed and the main circuit is simulated by Simulink module in Matlab, which verifies the correctness of the design.