Polyvinyl alcohol defoamer can effectively solve these foam problems in the chemical industry as a polymeric emulsifier, dispersant and polyvinyl formal, acetal, butyral resin and other industries. At the same time, it can also be used in the textile industry. For example, warp yarn sizing agent, fabric finishing agent and vinylon fiber raw material can be used. In agriculture, it can also control, inhibit and eliminate soil conditioner, pesticide adhesion synergist and polyvinyl alcohol film and other industries. Foam. It is said that it can be used in these industries because it has good water solubility, diffusivity, permeability, fast defoaming speed, long foam suppression time, and its good stability will not occur with other substances in the product. The reaction will not affect the product quality, not only that, it can also effectively solve the foam problem, thereby improving the product quality.