The test was carried out by using type I biological seed coating agent（T₁）, type II biological seed coating agent（T₂） and chemical seed coating agent（T₃） to study the effect of seed coating agent on carbon metabolism and yield of red bean. The test showed that the treatment of type I biological seed coating agent and chemical seed coating agent significantly reduced the plant height during the branching stage, and the type II biological seed coating agent significantly increased the plant height during the branching stage and flowering and pod-forming stage; all the coating agents were treated at The seedling stage significantly reduced the starch content, and significantly increased the sucrose and total sugar content during the branching period; the number of grains of the red bean per plant treated by the type I biological seed coating agent and the chemical seed coating agent increased by 29.48%and 71.91%, respectively. The treatment of the coating agent was reduced by 25.8%; The treatment of the type II biological seed coating agent and the chemical seed coating agent significantly reduced the 100-grain weight; the treatment of the type I biological seed coating agent and the chemical seed coating agent increased the yield by 29.69% and 23.32%, respectively. This indicates that the type I biological seed coating agent can effectively optimize the growth of red bean and increase the yield. This study provides a preliminary theoretical basis for the quality improvement of red bean and the application of biological seed coating in the direction of miscellaneous grains.