The invention discloses an anticorrosive agent for wooden product surface coating and a preparation method of the anticorrosive agent. The anticorrosive agent is prepared from the following raw materials in parts by weight: 75-80 parts of dry vegetable oil, 0.5-1 part of a cross-linking agent, 1-5 parts of a penetrating agent, 0.5-1 part of an antioxidant and 13-23 parts of an antifouling flame retardant. The natural vegetable oil is used as a main raw material, the anticorrosive agent contains no volatile solvent and gases which have adverse effects on the health of people, animals and plants; the anticorrosive agent is healthy and environment-friendly in the whole manufacturing and using process. The conjugation relationship of double bonds in molecules is improved through oxidation prepolymerization and radiation polymerization, the synthesis time is short, the energy consumption is low, the end point is easy to control, and the yield is high; a small amount of a rare earth drier isused as a cross-linking agent for radiation polymerization, so that deep-color toxic heavy metal substances contained in a final product are avoided, and meanwhile, a relatively good drying rate anda relatively good fresh-keeping effect can be achieved.