Aqueous polyurethane waterproof paint and preparation method thereof

The invention provides an aqueous polyurethane waterproof paint and a preparation method thereof. The paint comprises a component A and a component B, wherein the component A is composed of polyurethane performed polymer, N-methylolacrylamide and citric acid, and the component B is composed of an inorganic filling material, a plasticizer, a cross-linking agent, an emulsifier, an antifoaming agent, a catalyst, pigment and water. The preparation method comprises the following steps: successively adding N-methylolacrylamide and citric acid according to desired weight parts, carrying out stirring and heating, adding the polyurethane performed polymer in one shot before temperature rises to 62 DEG C, then carrying out heating to 82 DEG C, carrying out a reaction at a constant temperature of 83 to 85 DEG C for 2 to 3 h and then carrying out cooling to 52 to 54 DEG C so as to obtain the component A; successively adding raw materials of the component B into a reaction vessel stirrer according to desired weight parts, carrying out uniform mixing through stirring and grinding the mixed materials to a fineness of 51 to 55 [mu]m in a three-roller machine so as to obtain the component B; and uniformly mixing the component A with the component B according to a weight ratio of 1: 2 so as to obtain the aqueous polyurethane waterproof paint. The aqueous polyurethane waterproof paint has the characteristics of high temperature resistance, good weatherability, good waterproof performance, etc.