In order to design the drying equipment which has the advantages of low cost, low energy consumption and high efficiency for farmers, a kind of small rapeseed layered bed-typed drying equipment is manufactured. The equipment uses a biomass semi-gasification combustion furnace which burns straw and wood as the heat supply, heats the air by a heat exchanger, and dries rapeseed by the exchange of air. The numerical simulation based on computational fluid dynamics （CFD） and porous medium model was carried out to analyze the distribution of airflow in the drying chamber. An optimization scheme was put forward to improve the dry uniformity. The result shows that the drying equipment can meet the requirements of rapeseed drying. There is dead zone in the drying chamber when the drying only relies on the longitudinal ventilation. The combination of transverse and longitudinal ventilation has higher dry uniformity and drying efficiency than single longitudinal ventilation. It increases the air contact area between rapeseed and hot air and the uniformity of wind velocity distribution in the drying chamber. The use of biomass energy can achieve the requirement of energy conservation and emission reduction.