NOVELTY - A water polyurethane coating comprises primer and finish paint. The primer is a double-component primer that takes water hydroxyl acrylic acid dispersion as base resin, and water dispersing-type isocyanate with propylene glycol methyl ether acetate as curing agent. The finish paint is double-component finish paint that takes water hydroxyl acrylic acid dispersion as base resin and water dispersing-type isocyanate as curing agent.    USE - A water polyurethane coating for coating and protecting blade of wind driven generator (claimed).    ADVANTAGE - The primer and the finish paint are compatible, which are complementary in performance and are overlapped in functions. The performance of the coating can meet the conventional index, and the coating is also ultraviolet aging resistant, sand abrasion resistant, snow icing resistance, and long in service life.    DETAILED DESCRIPTION - A water polyurethane coating comprising primer and finish paint. The primer is a double-component primer that takes water hydroxyl acrylic acid dispersion A145 (RTM: Aqueous hydroxyl-functional polyacrylic dispersion) as base resin, and water dispersing-type isocyanate 304 (RTM: aliphatic water-dispersible polyisocyanate based on hexamethylene diisocyanate) added with propylene glycol methyl ether acetate as curing agent. The finish paint is double-component finish paint that takes water hydroxyl acrylic acid dispersion A145 (RTM: Aqueous hydroxyl-functional polyacrylic dispersion) as base resin, and water dispersing-type isocyanate XP2547 (RTM: Water-dispersible polyisocyanate based on hexamethylene diisocyanate) as curing agent. The primer comprises component A and component B. The component A comprises (pts. wt.) water hydroxyl acrylic acid dispersion A145 (RTM: Aqueous hydroxyl-functional polyacrylic dispersion)(50-60), rutile titanium dioxide powder (18-22), silicon aluminum-base hollow micro-bead (5-6), sericite powder (5-6), sheet-shaped graphite powder (5-6), deionized water (7-10), dispersing agent BYK-182 (RTM: Wetting and dispersing additive) (0.5-0.8), antifoaming agent BYK-024 (RTM: Defoamer) (0.2-0.6), base material wetting agent BYK-346 (RTM: Silicone surfactant) (0.2-0.6), sterilizing agent (0.1-0.4), and thickening agent PW25 (RTM: Pseudoplastic polyurethane thickener)(0.1-0.4). The component B comprises (pts. wt.) water dispersing-type isocyanate 304 (RTM: water-dispersed aliphatic polyisocyanate resin) (15-18) and propylene glycol methyl ether acetate (3-4). The finish paint comprises component A and component B. The component A comprises (pts. wt.) water hydroxyl acrylic acid dispersion A145 (RTM: Aqueous hydroxyl-functional polyacrylic dispersion) (55-65), rutile titanium dioxide powder (18-22), nano-silicon oxide slurry (10-12), fluorine silicon water repellent agent (2-4), rheological agent RM-8W (RTM: Rheological modifier) (0.1-0.4), rheological agent RM-2020 (RTM: Non-ionic urethane rheology modifier) (0.1-0.4), deionized water (3-6), dispersing agent BYK-182 (RTM: Wetting and dispersing additive) (0.4-0.8), antifoaming agent BYK-024 (RTM: Silicone defoamer) (0.2-0.4), base material wetting agent BYK-346 (RTM: Silicone surfactant) (0.2-0.4), and sterilizing agent (0.1-0.4). The component B comprises (pts. wt.) water dispersing-type isocyanate XP2547 (RTM: Water-dispersible polyisocyanate based on hexamethylene diisocyanate) (14-24). An INDEPENDENT CLAIM is included for a method for preparing a water polyurethane coating comprising stirring and adding dispersing agent, antifoaming agent, base material wetting agent, sterilizing agent, thickening agent, rutile titanium dioxide powder, sheet-shaped graphite powder, and sericite powder into de-ionized water;dispersing for 30 minutes at high speed; grinding until the fineness is 15 mu m; stirring; adding into the water hydroxyl acrylic acid dispersion, silicon aluminum-base hollow micro-bead, polishing powder, fluorine silicon water repellent agent; stirring for 20-30 minutes; regulating the color; thickening until reaching the viscosity; filtering and packaging; preparing component B by mixing water dispersing-type isocyanate with the propylene glycol methyl ether acetate for preparing curing agent; preparing finish paint by stirring and adding the dispersing agent, antifoaming agent, base material wetting agent, sterilizing agent, nano-silicon oxide slurry, rutile titanium dioxide powder; dispersing for 30 minutes at high speed; grinding until the fineness is 15 mu m; stirring; adding into the water hydroxyl acrylic acid dispersion, polishing powder, fluorine silicon water repellent agent, rheological agent, and rheological agent; stirring for 20-30 minutes; regulating the color; thickening until reaching the viscosity; filtering and packaging; and preparing component B by preparing curing agent from water dispersing-type isocyanate. The mass ratio of the component A to the component B is isocyanate:hydroxide (-NCO:-OH) of 1.5:1.8-1.