(1) Insecticides and fungicides in the seed coating agent which can effectively prevent and control plant diseases and insect pests at seedling stage are wrapped in the coating on the surface of seeds, and released slowly at seedling stage of eggplant, and the drug effect lasts for 30-60 days, and the effect of preventing and controlling plant diseases and insect pests at seedling stage can reach 65%-90%. (2) Promote seedling growth and increase crop yield. The active substances such as hormones and fertilizers in the seed coating agent are slowly released at the seedling stage of crops, which can promote the emergence of seedlings, regulate the growth of seedlings, enhance the stress resistance, and finally increase the yield by 5% ~ 20%. (3) Save seeds and medicines and reduce production costs. The existence of active ingredients in seed coat can effectively reduce the rate of rotten seeds and dead seedlings after sowing, and ensure the integrity and Miao Zhuang of seedlings; At the same time, the coated seeds are of high quality, which can be sown accurately, greatly saving the dosage of seeds, usually saving 10% ~ 30%. Because the pesticide in seed coat has a long effective period, it can reduce the number and dosage of drugs and save labor. (4) Reducing environmental pollution, the seed coating agent for protecting natural enemies can change the application mode at seedling stage from open air to concealment, especially the dosage added in the seed coating agent can be ignored compared with any application mode in the field, thus effectively reducing environmental pollution. (5) It is convenient for machine sowing and even sowing. After pelleting and coating, the volume and weight of small seeds are increased, and the shape and size are uniform, which is beneficial to mechanized sowing and uniform sowing. (6) Promote the standardization of improved varieties and prevent the circulation of fake and shoddy seeds. The seeds are pre-selected before coating, and the seed coating agent contains special pigments, which not only ensures the standardization of improved varieties, but also effectively prevents the circulation of fake and shoddy seeds and accelerates the process of seed industrialization.