Aiming at the problems that the irregular shape of wheat seeds leads to the high missing rate，low seed-filling qualified rate and difficult precision sowing of the traditional type hole wheel seed metering device under high-speed operation，a limited seed filling posture and combined type of positive and negative air pressure and wheat precision seed metering device was designed. The mechanical model of wheat seed was established by analyzing the movement and force of wheat seed during seed metering. The posture of seed filling was limited and the phenomenon of seed jamming was improved by adding arc-shaped auxiliary seed filling plate and seed stirring plate. The key structural parameters of the seed metering device were designed and calculated by analyzing the seed filling process and the distribution of seeds in the seed ditch，including the diameter of the type hole wheel was 100mm，the length of the hole was 8mm，the width of the hole was 5mm，and the depth of the hole was 3mm，etc. The optimum angle of arcshaped auxiliary seed filling plate was determined to be 5°through the simulation analysis with EDEM software. On the basis of the above research，the quadratic orthogonal rotation combination test of three factors and three levels was carried out with the rotary speed of type hole wheel，the vacuum degree and the rotary speed of seed stirring plate as the test factors and the seedfilling qualified rate，and the missing rate and the multiple rate as the evaluation indexes. The regression equation between the evaluation index and the test factors was constructed，and the significance of the influence of each test factor on the index was analyzed. By optimizing the test parameters，the optimal parameter combination was obtained：the rotary speed of type hole wheel was 66.27r/min，the vacuum degree was 3.52kPa，and the rotary speed of seed stirring disk was 52.00r/min. Under the conditions of above factors，the test verification was carried out，the seed-filling qualified rate was 92.70%，the missing rate was 3.47%，and the multiple rate was 3.83%. The experimental results showed that there was little difference between it and the optimization results，which showed that the seed metering device could meet the performance requirements of precision sowing for wheat.