In order to solve the problem of high energy consumption of desiccant wheel dehumidification and realize the energy-saving, high-quality and drying of agricultural products, the desiccant wheel dehumidification system was designed and optimized. And a middle and low temperature switchable integrated dryer was developed, and a fractional condensation mode was built. Fractional condensation and shii-take drying experiments were carried out. To test and improve the performance of fractional condensation, with the goal of increasing the regeneration heating temperature, Q1 and Q2, the Box-Benhnken response surface test was performed on three factors that affecting the classification performance: evaporating inlet air temperature, condensing air temperature, and damper opening. Through data analysis, a response surface model was established, and the influence mechanism of the above three inspection indicators affected by changes in the value of the three experimental factors was analyzed in combination with the contour map. At the same time, comprehensive optimization and experimental verification of each influencing factor were performed. The results showed that the RSq of the three models were all greater than 99%. The test factors had a great impact on the drying quality and energy consumption. When the inlet air temperature was 34.2℃, the condensing air temperature was 34.1℃, the damper opening was 82.3%, the heating temperature was 67.1℃，Q1 was 11030kJ, Q2 was 21449kJ, and the prediction error were less than 6%. At room temperature, as much as possible to promote the evaporation temperature and regeneration inlet air temperature was conducive to improving the effect of classification regeneration. It can reduce energy consumption by 29.6% compared with pure electric heating regeneration. The test of shii-take drying for desiccant wheel dehumidification showed that at the same drying temperature, it was better than the shii-take mushroom dried by the heat pump, the drying rate was increased by more than 2 times, and the energy consumption was higher than 5.9%. The research result can provide a reference for the design of energy saving drying system for desiccant wheel dehumidification.