At present, polyether modified silicone oil PESO is one of the most widely produced and applied silicone oil, which is polymerized by connecting the main chain or side chain of linear dimethyl silicone oil with polyether chain, and is the most widely produced and applied modified silicone oil in the market. The oxygen atoms in the polyether chain in the molecular structure of the silicone oil react with water to form hydrogen bonds, which can be dissolved in an aqueous solution. Polysiloxane segments are neither hydrophilic nor hydrophilic, nor are the hydrocarbon groups on their main chains. Therefore, the polyether chain segment and the polysiloxane chain segment are bonded together through the silicon-hydrogen addition reaction to form a unique non-ionic surfactant. Due to the wide variety of polyether, a series of polyether modified silicone oil will be generated with the change of the introduction method during the addition reaction, with different properties and functions, which can meet the needs of diversified markets.There are five main types of polyether modified silicone oil structures of PESO defoaming agent: AB type, ABA type or BAB type, (AB) type, side chain type and branch chain type. Among them, si-o-c type is the condensation of silicone oil and polyether, which belongs to the hydrolysis type. Literature studies [19] have shown that even with hydrolysis, the defoaming performance is still very significant.