Abstract: Based on the principle of mathematical modeling, this paper analyzes the key functional devices of air suction grain precision planter, optimizes the defects existing in the operation process of planter, and designs a grain precision planter. The field experimental data show that the average qualified rate of plant spacing in precision planter operation test is 87.67%, the average hole rate is 4.89%, and the average coefficient of variation of plant spacing is 23.89%. All indexes can meet the requirements of agronomic experts related to grain precision sowing.