The invention relates to a self-polishing antifouling paint and a preparation method thereof. Every 100 parts by mass of the antifouling paint is composed of 18-24 parts of solid-based resin, 50-55 parts of antifouling compound, 0.5-1.5 parts of graphene microchip, 3-6 parts of pigment and filler, 1-2 parts of dispersing agent, 1-2 parts of organobentonite and the balance of organic solvent. The resin is composed of a hydroxy acrylic resin, a zinc acrylate resin and rosin. The antifouling compound is composed of zinc pyrithione, 4,5-dichloro-2-n-octyl-4-isothiazolinyl-3-one, cuprous oxide and zinc oxide. The preparation method comprises the following steps: respectively preparing the graphene microchip-zinc oxide-hydroxy acrylic resin slurry and cuprous oxide-rosin-zinc acrylate slurry, and mixing to obtain the self-polishing antifouling paint. The obtained self-polishing antifouling paint product has the advantages of stable quality, long antifouling period, favorable polishing effect, high strength, cracking resistance and low VOC (volatile organic compound).