Preparation method of waterproof coating

The invention relates to a preparation method of a waterproof coating. The preparation method comprises A, uniformly mixing aliphatic polyisocyanate and an elastic isocyanate curing agent in a proportion to obtain the a component A, B, uniformly dispersing a high boiling point solvent and a nanometer material dispersing agent, adding an active superfine functional filler into the mixture, and carrying out high-speed dispersion to obtain active ultrafine functional filler slurry, C, uniformly dispersing polyaspartic acid ester resin, polymeric modified polyaspartic acid ester resin, a dispersant, a leveling agent and a defoamer, D, adding filler and pigment and the active ultrafine functional filler slurry obtained by the step B into the mixture obtained by the step C and carrying out high speed dispersion or grinding to obtain a component B, and E, mixing the component A and the component B in a mass proportion to obtain the waterproof coating. Through the active ultrafine functional filler, adhesive strength, hydrophobicity, hydrolysis resistance and weatherability of the coating are improved.