The invention discloses a preparation method of automobile paint, which belongs to the technical field of paint. The coating is composed of a main agent and a curing agent, and the main agent includes the following raw materials: polyaspartic resin, nano-titanium dioxide, water-based polyurethane resin, methacrylic acid, polyoxyethylene oleate, water, titanium dioxide, anti-settling agent , dispersant, leveling agent, defoamer, wetting agent, triethylamine, ethylene glycol butyl ether; the curing agent includes the following raw materials: isocyanate resin, catalyst. The invention is prepared through the steps of water-based polyurethane resin preparation, main agent preparation, mixing and the like. In the present invention, the reinforcing system composed of nano-titanium dioxide, water-based polyurethane resin, methacrylic acid, and polyoxyethylene oleate is used in the automotive coating of the present invention to improve the tensile strength, elongation at break, and low temperature resistance of the automotive coating. Sex, reduce paint fineness, improve paint stability.