The invention discloses an automobile coating and a preparation method thereof, and belongs to the technical field of coatings. The coating comprises a main agent and a curing agent, and the main agent comprises polyaspartic acid resin, nanometer titanium dioxide, waterborne polyurethane resin, methacrylic acid, polyoxyethylene oleate, water, titanium dioxide, an anti-settling agent, a dispersant,a leveling agent, an antifoaming agent, a wetting agent, triethylamine and ethylene glycol butyl ether; and the curing agent comprises isocyanate resin and a catalyst. The coating is prepared by thefollowing steps: preparation of the aqueous polyurethane resin, preparation of the main agent, and mixing. A reinforcing system formed by the nanometer titanium dioxide, waterborne polyurethane resin,methacrylic acid and polyoxyethylene oleate is used in the automobile coating to improve the tensile strength, the elongation at break and the low temperature resistance of the automobile coating, reduce the fineness of the coating and improve the stability of the coating.