Objective To improve the uniformity of airflow in the cold air fermentation room.Methods Numerical simulations were performed using Fluent software, with average velocity and velocity non-uniformity coefficient as evaluation indexes. Under constant supply air volume, the influence of inlet duct taper on the airflow at each supply air outlet was studied. The distribution characteristics of airflow velocity in the cross-section of the fermentation room under different air supply methods were examined. A circulating air supply mode was then developed, and the optimal time proportion of each air supply method within a cycle was analyzed.Results As the taper of the inlet duct increased, the airflow at the starting supply port gradually decreased, while the airflow at the end increased. The best air supply uniformity in the inlet duct was achieved when the taper was 7∶5. Compared with double-sided air supply, single-side air supply resulted in a higher average speed, which is beneficial for moisture evaporation. However, the uniformity of the flow field was poor, which decreased the material quality. In the circulating air supply mode, the best uniformity of the flow field velocity was achieved when the working time of the double-sided, left-side, and right-side air supply accounted for 64%, 18%, and 18% of the cycle, respectively. Compared to single double-sided air supply, the uniformity of the flow field velocity improved by 16.4%, and the average speed increased by 13.2%.Conclusion By improving the inlet duct taper and optimizing the air supply mode, the uniformity of airflow in the cold air fermentation room was enhanced.