The study was conducted for water-based coatings, focusing on the defoaming properties and color spreading properties of water-based coatings. By adjusting the formula, we studied the effect of water-based defoamer on coating foam and analyzed its mechanism of action. The water-based coating defoamer is made of low hydrogen silicone oil, allyl polyether as raw material, and chloroplatinic acid as catalyst to synthesize polyether-modified polysiloxane and then compound it with emulsifier, thickener, silicone paste, silica, etc. to make organosilicon defoamer.                     1, Water-based coating defoamer composition ratio The ratio of Si-H to C=C of polyether modified polysiloxane is 1:1.1, the polyether drop addition time is 3 h, the reaction time is 6 h, the reaction temperature is 130℃, and the active hydrogen conversion rate is 82.8%. Research shows that the polyether-modified polysiloxane formulated silicone defoamer in water-based coatings has excellent defoaming effect and good compatibility with the system for long-lasting foam inhibition performance. 2, Water-based coating defoamer performance For water-based coatings foam problem we have selected a typical interior wall emulsion paint formula to compare the defoaming properties of mineral oil and silicone defoamer, through the simulation of field construction to compare the defoaming effect and compatibility of defoamer. The study shows that the defoaming effect of silicone defoamer is better than mineral oil defoamer but the compatibility is poor. Regarding the color spread of water-based coatings, we selected typical interior wall emulsion paints for comparison, and tested the effect of adding different types and amounts of wetting agents on the color spread of the color paste and finally obtained a more satisfactory result. 3, Water-based paint defoamer application Through continuous experiments, we have successfully prepared defoamer for water-based coatings, which is not easy to break emulsion and has good compatibility in coatings, and the high active component of the product will not produce shrinkage to coatings. The cost of raw materials is lower and there is no pollution emission, so the economic and social benefits are better. 4, Micronized waxes for water-based paint