To discuss the operating characteristics of a new kind of energy-storage air source heat pump when supplying hot water, the unit’s performance in different conditions was studied by experiments. The results show that the unit can operate efficiently and stably, and the unit’s mean REE reduces with the increase of hot water supply flux. There also exists a break of hot water supply because the high flow rate of circulation water causes intensive disturbance in the heat storage tank, and the time of break is prolonged with the decrease of outdoor temperature. Moreover, the heat supple ability and mean REE of the unit reduces with the decrease of outdoor temperature.