A three-dimensional numerical model included the inside and outside environment of the cold store, and air curtain of the big cold store was established in this study. The steady and unsteady simulations of the temperature field were performed by using numerical simulation software, and the relative results were used for experimental verification. It turned out that experimental verification was basically coincidence with the results of the simulations. Acquired from analyzing the results of simulations, although the temperature field in the cold store reached the required temperature range, the distribution of temperature field near stacking goods was not balance completely, due to the obvious temperature difference between goods and other areas in the cold store. When the supply velocity of the air curtain was 8 m/s under the unsteady condition, the temperature field of the cold store had the smallest fluctuation and the air curtain had the highest efficiency. We put forward suggestions that it could be optimized in future, including the change of air flow patterns in a cold store, the stacking ways and height of goods, and other parameters of the air curtain.