The hot-air drying dynamics model of Daqu during the period of drainage and cooling was established in this study to explore the correlation between hot-air drying and the lethality of Daqu pest by investigating the hot-air drying characteristics, the effective diffusion coefficient (Deff) and the activation energy (Ea) of Daqu. The results demonstrated that the drying stage of Daqu was mainly the deceleration-drying stage. The effect of drying temperature on Deff was obviously greater than the drying air speed, indicating the temperature had a great influence on the dehydration of Daqu, and the Ea was 59.744 kJ/mol. In addition, eight typical drying model equations were selected to describe the drying curve of Daqu during the desiccation-cooling period. The Midilli model had superior fitting effect and high fitting accuracy, and the Daqu pests in external and internal environment would completely die after hot-air drying process. Therefore, the paper investigated the drying technology of Daqu with external heating process, and the Daqu pests were effectively exterminated. The obtained results provided a theoretical basis for research and production control of hot-air drying process of Daqu.