Taking a cold store as the experimental objective, the inside environment, air curtain and outside environment of the cold store were simulated by a 3D coupled model. The unsteady simulation of the flow field of the air curtain was performed by using a CFD software and the temperature field inside the cold store was measured. The effects of the supply velocity, supply angle and jet width of the air curtain on its isolation ability were analyzed under the condition that the door and the air curtain were opened simultaneously. The results show that there is an optimal supply velocity and angle to make the air curtain has its best isolation performance and the temperature field inside the cold store has the smallest fluctuation. However, the jet width should not be too large. The optimal supply velocity, angle and jet width of the air curtain for this cold store are 8m/s, 15° and 0.04m, respectively.