General organic compounds such as ether, hydrocarbons, alcohols and phosphate esters, the spread coefficient is large, so the role of breaking bubbles is strong, but the role of bubble suppression is very poor. Polyether prepared by cyclo-opening polymerization of ethylene oxide and propylene oxide is an excellent water-soluble non-ionic surfactant with typical structure of CnH2n+1O (EO) a (PO) bH. The polyepoxyethane linkage is hydrophilic and the polyepoxyepropane linkage is hydrophobic. Polyethers dissolve in water when the amount of ethylene oxide exceeds 25%. The index of water solubility of polyether is cloud point. Surfactants with different hydrophilic equilibrium values (HLBS) can be prepared by adjusting the ratio of ethylene oxide and propylene oxide to obtain the desired surface activity. By adjusting EO/PO ratio and relative molecular weight and improving its water solubility and oil solubility, the surface tension of foaming liquid can be greatly reduced, and it has good anti-foaming and anti-foaming ability. The biggest advantage of polyether defoaming agent is strong anti-foaming ability, so it is currently the leading defoaming agent used in the fermentation industry, but it has a fatal disadvantage is low foaming rate, once a lot of foam is produced, it can not be effectively extinguished, but need a new amount of defoaming agent to slowly solve the problem.