This study is concerned with a new reverse-cycle hot gas method using phase change thermal energy storage (TES) to eliminate frost in an air-source heat pump (ASHP), which can effectively solve the shortage of defrosting energy. The feasibility of defrosting was investigated through experiments and the modes' performances were compared with a nominal 850 W capacity ASHP system conventional reverse-cycle hot gas defrosting method. The results have indicated that thermal energy storage based reverse-cycle hot gas method can improve the discharge and suction pressure and shorten defrosting time in defrosting. In defrosting operation, the TES defrosting method can improve discharge and suction pressure by 0.25 MPa and 0.15 MPa respectively, and shorten defrosting time by 60% in the tested environment, relative to the conventional reverse-cycle hot gas defrosting method.