A preparation method of a silicone modified acrylic hydrogel antifouling coating comprises the following steps: synthesizing silicone modified acrylic resin, and preparing the hydrogel antifouling coating. The antifouling coating is a double-component coating composed of a component A and a component B, and a mass ratio of the component A to the component B is 8:1, wherein the component A is a resin base material carrier, and comprises, by mass, 55-65 parts of the silicone modified acrylic resin, 4-6 parts of iron oxide red, 0.5-1.5 parts of organic bentonite, 4-6 parts of zinc oxide, 7-9 parts of copper pyrithione, 8-10 parts of a Sea-Nine211 antifouling agent and 10-12 parts of an organic solvent; and the component B is a cross-linking agent carrier, and comprises, by mass, 25-35 parts of an aziridine cross-linking agent, 60-70 parts of n-butanol and 4-6 parts of water. Silicone is introduced to the acrylic resin system through a chemical technology, and a proper assistant and the proper antifouling agent are matched to form a low-surface organosilicon antifouling barrier layer, so the coating has self-layering and self-restoration effects, simple process, good antifouling effect, small dosage of the antifouling agent, and effective prolongation of the antifouling time period.