To make the food be dried better as well as improve the drying efficiency, based on the analysis of the working principle of rotary disc dryer, for its critical part drying tray, the geometry structure design, the stress and its deformation were analyzed. Moreover, the calculating formulas of the thickness of the steel material manufactured for the drying tray were also provided. After analyzing the heat transfer process between drying tray and bulk solids bed in the work, the heat transfer coefficient formula was then summed up. According to the relevant theory given in this study, rotary disc dryer was built and ran well, and its drying effect was remarkable.