Currently, numerical simulations are conducted at the level of dryers without considering the actual moisture evaporation within agricultural materials. This departure from reality fails to meet the requirements of actual industrial production. To address this issue, this paper proposes a drying kinetic derivative model based on experiments conducted on shiitake mushrooms' drying kinetics. With the help of this model, we can determine the moisture evaporation rate under varying drying conditions. Based on the evaporation rate, a material-dryer integrated simulation method is developed to achieve coupling between the material and the dryer. Finally, the simulation method is used to investigate the non-uniform distribution of the moisture ratio of shiitake mushrooms in the dryer, optimize the inlet parameters of the dryer, and improve its internal structure. Through optimization, it was determined that the optimal angle for the baffle is 45° with a width of 65 mm, which can reduce the unevenness of moisture content by 25.84% and decrease the total drying time by 0.59 h. This research not only contributes to the thorough analysis of the distribution of various physical fields within the dryer, optimization of drying conditions, and structural parameters of the dryer but also offers valuable reference for studying and optimizing the drying industrial conditions of other materials. This research holds significant implications for the industrial advancement of the drying sector.