Abstract: Aiming at the high cost of filler iron red and zinc powder in epoxy coatings, as well as the low utilization rate of steel slag with large output, shield powder was obtained through the synergistic modification of steel slag with phosphoric acid and the silane coupling agent KH550, and characterized by FTIR, XRD, XPS, TEM, SEM and LPSA, then shield powder was incorporated into epoxy coatings to produce shield powder-based epoxy composite anticorrosive coatings. The mechanical properties of the composite coatings were investigated. Its anticorrosive performance was tested through salt spray and salt immersion tests, and characterized using SEM and electrochemical methods. The results show that the addition of shield powder significantly improves the mechanical and anticorrosive properties of the composite coating. Specifically, when the shield powder is added at 15wt%, the properties of the coatings are significantly enhanced, with hardness, adhesion, and flexibility reaching 0.29, level 1, and 1 mm, respectively, the friction mass loss is only 49.7 mg, with the water absorption rate of just 0.51wt%, and the water contact angle of 115.7°. The impedance modulus, corrosion potential and corrosion current are 1.6×10⁸ Ω·cm², 0.443 V and 3.95×10⁻⁷ A·cm⁻², respectively. The silane coupling agent KH550 grafts on the surface of the shield powder significantly improves its dispersion uniformity and enhances the interfacial compatibility between the shield power and epoxy resin. This contributes to a denser coating surface and reduces the penetration of corrosive media, thus further enhances its anti-corrosion performance.