In order to ensure the quality of rice in long-term storage, it is of great significance to simulate and analyze the horizontal cooling and water-retaining ventilation under the conditions of same humidity and different ventilation temperatures. Based on the heat and mass transfer theory of hygroscopic porous media, this study applied the existing mathematical model of heat and moisture transfer of grain reactor, and analyzed the change rule of different air inlet temperature on the temperature and moisture of grain storage barn under the same humidity with the numerical simulation method. The results showed that when the initial temperature of the grain reactor was 25 ℃ and the air inlet temperature was 17 ℃, the cooling rate of the grain reactor was the fastest and the moisture absorption and desorption of grain reached the balance first, and the water retention effect inside the grain reactor was the best. When coupling heat and moisture transfer was carried out between the grain layer 0.4 m away from the air inlet and the air inlet at different temperatures, the grain layer temperature and moisture decreased in the same trend. The higher the air inlet temperature was, the more obvious the moisture loss was. The lower the inlet air temperature was, the greater the drop in grain stack temperature was. As the distance between the grain layer and the air inlet increased, the cooling effect of the grain layer became worse. When the ventilation temperature was 19 ℃, the temperature of the grain layer 26.2 m away from the air outlet almost kept the initial temperature of the granary unchanged, so the cooling effect cannot be achieved.