In order to solve the problem of the mismatched supply and demand of cooling capacity in the cooling system，the charging and discharging characteristics of the chilled water storage tank are simulated through software.The influences of the position of the perforated plate，the pore diameter of the perforated plate and the opening ratio on the thickness of the thermocline layer in the tank and the charging and discharging efficiency are studied，and verified through experiments.The results show that improving the structure of the orifice plate can reduce the thickness of the thermocline layer and improve the charging and discharging efficiency.When the chilled water storage tank under study has the best effect，the pore diameter of the orifice plate is 20 mm，the opening ratio is 40%，and it is set in the middle position of the chilled water storage tank.Compared with the situation where the orifice plate is placed at the lower part，the charging and discharging efficiency of this structure is increased by 5.2% and 5.4% respectively.Compared with the opening ratio of 30%，the charging and discharging efficiency is increased by 3.2% and 2.1% respectively.Compared with the structure with an opening ratio of 50%，the charging and discharging efficiency is increased by 6.7% and 5.4% respectively.The research results can provide a reference for the optimized design of the cold storage water tanks.