Castor oil-based polyurethane acrylate (COPUA) was synthesized from isophorone diisocyanate (IPDI), castor oil (CO) and hydroxyethyl acrylate (HEA). Modified silica sol was prepared by sol-gel method with tetraethyl orthosilicate (TEOS) and 3- (isobutenyl oxide) propyl trimethoxysilane (MEMO). A series of modified silica sols were obtained by adjusting the ratio of TEOS to MEMO. The optimal ratio of MEMS to TEOS was determined to be 1 (MT-1). Based on this, the UV-cured COPUA/SiO2 hybrid material was obtained by changing the addition amount of MT-1. The hybrid materials and coatings were characterized by FT-IR, TEM, SEM, TGA, et al. the mechanical and surface properties of the composite coatings were also tested. The result showed that when the amount of modified silica sol is 15%(based on the mass of COPUA resin, the same below), the SiO2 particles in the coating are evenly distributed. The coating surface is smooth and flat, which can be proved by the excellent light transmittance(100.2%). The hardness of the composite coating is 5H, the adhesion is grade 0 and the flexibility is 1mm; The tensile strength of the film reaches 13.52MPa and the elongation of section is 7.49%,which has a good application prospect in the modification and protection of plastic surface.