The work aims to obtain the waterborne polyurethane coating material with anticorrosive and flame-retardant functions by hard segment and post-chain modification. The polyurethane prepolymer (FPU) was prepared and synthesized by taking diisocyanate, polypropylene glycol and dimethylolpropionic acid as basic units and phosphorus and nitrogen synergetic flame retardant (FRC-6) as chain extender of hard segment. The improved Hummers method was used to prepare graphene oxide (GO) which was taken as post-chain extender and added in the emulsion phase of waterborne polyurethane. The modified waterborne polyurethane materials (GOFPU) with high grafting rate graphene oxide were prepared by the reaction between oxygen-containing functional group like —OH in GO structure and NCO— in FPU. The structure and performance of GOFPU were characterized.. After modification of GO, the distribution of polyurethane emulsion participle changed along the direction in which the particle size increased. The average particle size of GOFPU increased to 90 μm and the viscosity of the emulsion reduced to the lowest value of 9 mPa?s. The grafting rate of GO and FPU was up to 89.2% at most. When the content of the GO was 0.4wt%, the corrosion resistance potential was 76 mV and the corrosion resistance was the best. When the content of the GO was 1.0wt%, the limiting oxygen index (LOI) of 30.5% reached the flame retardant level. Compared to waterborne polyurethane materials with the same content of fire retardant, the particle size of GOFPU emulsion increases, the viscosity decreases, the corrosion-resistant and flame retardation improve dramatically. Moreover, GOFPU was non-toxic and harmless, green and environmentally friendly.