The invention discloses a preparation method of flame-retardant and light-resistant waterborne polyurethane coating. The method comprises the steps of mixing 0.6g of a catalyst obtained in the step (1), 80g of polytetrahydrofuran ether glycol and 40g of isophorone diisocyanate in a 500ml four-necked flask provided with a stirring paddle, a temperature gauge and a condenser pipe, carrying out a reaction for 1h at the temperature of 70 DEG C, adding 0.2g of 2-sulfobenzoic anhydride and 0.05g of carboxylated graphene sheet obtained in the step (3) into the mixture, and carrying out a reaction for 2h at the temperature of 80 DEG C to obtain a polyurethane prepolymer A; adding 1.2g of aminobenzene sulfonic acid and 20g of acetone into the polyurethane prepolymer A, carrying out a reaction for 2h at the temperature of 75 DEG C, adding 1g of 2, 4, 6-trihydroxybenzoic acid and 1.2g of a light-resistant agent obtained in the step (2), carrying out a reaction for 0.5h at the temperature of 85 DEG C, adding 12g of triethylamine for carrying out a neutral reaction for 30min, and adding 110g of water for emulsifying to obtain the flame-retardant and light-resistant waterborne polyurethane coating. The prepared polyurethane coating is environmental-friendly and low in price, is widely used on the surfaces of walls, furniture and metal utensils, and can be used as an adhesive of plastics, glass, papermaking and textile.