Silicone polyether synthetic defoamer can keep a good physical state at 80 ℃ -100 ℃ of foaming system and strong alkali condition, without demulsification and bleaching oil, and the effect of defoaming is stronger than that of normal temperature. It can quickly eliminate the foam produced by resin acid soap, fatty acid soap. lignin sulfonate and other surfactants, which has a good effect in the pulping stage. White emulsion liquid with viscosity of 100g~500 mPa.s (25 ℃), PH = 7~8, active substance content: (30 ±1)%, Nonionic type, shelf life: 180 days (0 ~ 25 ℃).