An ultraviolet (UV)-curing polymer coating is an environmentally friendly coating with no volatile organic compound emissions, which can be used for surface protection of steel. However, pure organic polymer coatings cannot meet the needs of practical applications because of their low hardness, poor thermal stability, and high shrinkage rate. In this paper, different contents of mica particles were mixed into epoxy acrylates to prepare UV-curing organic–inorganic composite coatings. The inorganic material was used to enhance the thermal stability and corrosion resistance performance to solve part of the problems faced by a pure organic polymer coating. This paper discusses the UV-curing process of the composite coating, the distribution of particles in the matrix resin, the mechanical properties of the coating, and its thermal stability and corrosion resistance. The results show that the prepared composite coatings show significant improvements in thermal stability and corrosion resistance. Compared with the epoxy acrylate coating, the T10 of the mica-added composite coating with mica was increased by more than 100°C. At 15 g addition (373,070 Ω cm2), there was a 35 times improvement in the total impedance after immersion in 3.5 wt.% NaCl solution for 24 h compared to that of the epoxy acrylate coating (10,799 Ω cm2).