The invention discloses a high-solid varnish type oily acrylic resin for automobiles and a preparation method thereof, which belongs to the field of automobile coatings and solves the problems of low solid content, high viscosity and poor solubility in existing acrylic resin coatings. The resin of the present invention contains components acrylic acid, styrene, butyl acrylate, hydroxyethyl methacrylate, methyl methacrylate, methacrylic acid, butyl methacrylate, isooctyl acrylate, n-dodecyl mercaptan, Lauryl methacrylate, isobornyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, No. 100 mineral spirits, di-tert-amyl peroxide, glycidyl tert-carbonate and resin active diluent, the solid content can be Up to 90%, good dilution, low viscosity, self-made reactive diluent can greatly improve the water resistance and acid resistance of the coating, the construction solid content of the resin is nearly 70%, greatly reducing VOC emissions, environmentally friendly and practical.