Hot air drying is the key link of bulk grain and agricultural product processing. Because of the adjustment of national environmental protection and energy utilization policies in the new era, it is required to research and develop the energy saving technology of hot air drying for agricultural product. The current research is mostly limited to practical work tracking and empirical design, and there are also numerical calculations by heat and mass transfer theory. However these approaches have some limitations. Physical simulation is an effective potential method. In the process of studying the condensation increasing efficiency and energy saving technology, this paper has developed a test system which can simulate the actual hot air drying recycling energy. It has multi-parameter adjustable, graphical display drying state, energy consumption monitoring and other functions, and it can also provide effective means to study energy saving technology of hot air drying of agricultural product. The corn drying test for this system showed that energy recycling energy-saving drying could save energy 32%~56% when compared with ordinary open hot air drying.