In order to make the flow field distributed orderly in the air-assisted high speed maize precision seed metering device, thereby improving the working performance of the seed metering device, three kinds of structure type diversion turbine were designed. Through the simulation and theoretical analysis of CFD method, the diversion turbine can effectively improve the air flow inside the seeding device and increase air speed where type hole in outer ring. At the air flow rate, the pressing force was increased, and the C diversion turbine with a large windward angle and a curved structure had better disturbance and guiding, and the effect was optimal. In order to obtain the best performance parameters of the C diversion turbine installed, the operation velocity, quantity of feeding and wind pressure were used as test factors, and the qualified index, the missing index and the multiple index were used as test indicators. A three-factor quadratic rotation orthogonal combination test was performed and the multiple regression analysis and response surface analysis of the test data were carried out by Design-Expert 8.0.6 software, and the influence of various factors on the indicators was obtained. The multi-objective optimization method was used to determine the optimal combination of parameters: the operation velocity was 9.8km/h, the quantity of feeding was 1.8kg/min, and wind pressure was 8kPa and the qualified index of seed metering was the highest. At this time, the qualified index was 91.32%, the missing index was 2.83%, and the multiple index was 5.85%. The comparison verification test was carried out on the optimization results, and the comparison was made under the same conditions with the uninstalled diversion turbine seed metering device, and it was found that the installation of the diversion turbine can effectively improve the working performance of the seed metering device.