The present invention discloses a corn seed coating agent, and relates to a seed coating agent. The corn seed coating agent is characterized in that: the corn seed coating agent is prepared from the following raw materials, wherein the raw materials comprise 15-25 kg of a film-forming agent, 0.1-0.5 kg of 6BA, 1-5 kg of 1,1-dimethylpiperidinium choride, 40-60 kg of an insecticide and 15-25 kg of a fungicide; during preparing, the film-forming agent is added to the water according to a ratio of the film-forming agent to the water of 1:48-52 to prepare a water agent, then the other raw materials are added to the water agent to carry out uniform mixing to obtain the corn seed coating agent. The insecticide comprises imidacloprid and / or carbosulfan, wherein the weight ratio of the imidacloprid to the carbosulfan is 3-5:1 when the imidacloprid and the carbosulfan are added. The fungicide comprises difenoconazole. Other trace element fertilizer and microelements are added to the raw materials. The corn seed coating agent has the following advantages that: the corn seed coating agent contains the fungicide, the insecticide and the plant growth regulator; with adopting the corn seed coating agent, the seedling disease, the seed-transmitted bacteria, the soil-transmitted bacteria, and other diseases can be removed; the soil insect and the seedling diseases and insect pests can be prevented; the drug cost and the working hours for spraying the drug can be saved; the corn seed coating agent provides the benefit for improvement of the quality of the corn, and the yield of the corn can be generally increased by 15-20%.