In order to promote the application of heat storage device using phase change material (PCM), a water tank filled with sodium acetate trihydrate ball was designed, and its performance was studied. The effects of inlet temperature, flow rate on the charging and discharging time, hot water supply, thermal storage efficiency of PCM tank were analyzed through experiments and simulations. A new concept “heat loss rate of the heat exchange blind area” was put forward, by which the impact of PCM ball position on the heat exchange blind area was analyzed. The results show that with the increase of inlet temperature and flow rate, the charging and discharging time decrease. The hot water supply and the thermal storage efficiency reaches their maximum value (28.3L/h, 78 %) at the flow rate of 25L/h and the inlet temperature of 80 °C. When the height of the bracket in PCM tank is 60 mm, the heat loss rate of heat exchange blind area decreases by 47 %. The best height of PCM balls is 90 mm, which increases the average temperature of heat exchange blind area by 1.8 %. The study has guided significance for the practical application of water tank with phase change thermal storage module.