The work aims to solve complex steel structure anti-corrosion repair problems in marine environment, improve service life of steel structures such as offshore platforms and guarantee safe operation of offshore platforms. Polyurethane prepolymer was synthesized from dihydroxy polyether, trihydroxy polyether and toluene diisocyanate (TDI), and the synthesis reaction parameters were studied. On this basis, pigment, filler and additive of water-cured paint were investigated with water-cured resin as base material. Optimum conditions of polyurethane synthesis process were: polyether polyol mass ratio of 7:1, synthesis temperature of 70 ℃ and reaction time of 4 hours. The water-cured paint was prepared with 10% filler consisting of talc, mica powder and carbon black as well as 0.5% catalyst dibutyltin dilaurate. The anticorrosion repair material of marine complex steel structure was prepared with non-woven fabric as carrier. Key parameters including dihydroxy polyether/trihydroxy polyether ratio, synthesis temperature and synthesis reaction time are determined by optimizing synthesis conditions of water-cured resin. Water-cured paint exhibiting better properties is prepared by selecting pigment, filler and catalyst. On this basis, anticorrosion repair material applicable to complex marine steel structure is prepared with non-woven fabric as carrier.