Abstract: Phase change heat storage technology plays an important role in the field of solar heating. In order to improve solar energy utilization,a set of phase change heat storage device was designed,the influence factors of the spherical phase change heat storage unit were studied,keeping the total mass of the phase change material（PCM）in a small changing range. The heat storage performance of the device was explored through comparing the different diameters,porosity,and interlayer spacing. Experimental and simulation results show that: under the same conditions,the smaller the diameter of the phase change ball,the shorter time for charging heat. Considering the processing difficulty and manufacturing cost,the heat storage ball with a diameter of 46 mm or 50 mm is the best choice; the porosity,inlet temperature and inlet flow have a greater impact on the overall charging heat time; on the contrary,changing the distance between the heat storage balls has smaller effect on the charging heat time.