Abstract: Abstract: In solar water heating system, the discordance of heat energy collection and use time makes the hot water storage tank play a vital role in the whole system. Therefore, how to improve the thermal storage performance of the hot water storage tank has become one of the hot spots in industry research. Among many measures, as an effective method, setting barriers in the water storage tank has been adopted by more and more people. Its principle is to optimize the structure of temperature field in water tank by setting barriers to change the flow field structure. In this paper, in order to study the influence of the barrier with the same hole area and different numbers of hole in the solar water storage tank on thermal stratification and thermal storage performance, the process of heat transfer in a water tank with different openings is analyzed numerically by standard k-ε model under different flow parameters. The results show that: when the inlet temperatures of hot water and cold water is 333 and 303 K and the inlet velocity of hot water and cold water is 0.05 and 0.5 m/s, respectively, the water storage tank with a hole area of 0.007 9 m2 has the highest thermal stratification efficiency, 2.341. When the hole area is the same as 0.0314 m2, installing the barrier with five holes will significantly expand the volume of high-temperature water in the water tank compared with installing the barrier with one hole. The number of holes has a weak influence on the outlet temperature difference between the hot and cold water of the tank, but the larger the hole area, the more obvious the influence of the numbers of hole on the Richardson number. If the user's water consumption changes within a certain range, the Richardson number decreases with the increase of the user's water consumption, and the heat stratification is more likely broken when the inlet velocity of cold water is lower than 0.3 m/s. The maximum relative deviation of the outlet temperature of hot water corresponding to the inlet temperature of hot water of 333 and 343 K is 0.22%, but these two working conditions have little effect on the outlet temperature of cold water. In this study, by calculating and comparing the heat transfer process in the solar water storage tank under the condition of the same hole area on barrier, the effects of different flow parameters and different arrangement of holes on barrier on the thermal stratification and thermal storage performance of the solar water storage tank are compared and analyzed, which has certain theoretical reference for the optimization design of barrier structure with openings in liquid separation equipment in different researches of various industries. In addition, due to the randomness of solar radiation intensity in practical engineering, if the fluid parameters are given, the way of combining solar water storage tank and auxiliary heat source to meet the needs of different users should be considered.