The invention discloses a preparation method of a high-strength, anti-fouling and anti-drag soft hydrogel coating. The preparation method comprises steps as follows: a base material with rich double bonds on the surface is obtained through pretreatment by a silane coupling agent, flexible first network hydrogel is formed on the surface of the pretreated base with a photo induced polymerization method, rigid zwitterionic polymer chains are introduced through photo induced polymerization, a rigid-flexible double network hydrogel coating is obtained and placed in water until swelling equilibriumis realized, and the high-strength, anti-fouling and anti-drag soft hydrogel coating with the smooth surface is obtained. The preparation method can be implemented at the room temperature, the processis simple and practical, the raw materials are easily available, the cost is lower, and the method is suitable for industrial production. The coating has good application prospect in the field of preparation of anti-fouling and anti-drag materials for ships and biomedical coating materials.