Preparation of polyether-modified silicone, and then by mechanical emulsification polyether modified silicone, span-tween the composite emulsifier and a paste made of silicon, obtained polyether-modified silicone defoamer . The results show that when the content of silica and a polyether-modified polysiloxane was 6%, span-tween the mass fraction of emulsifier is 3% polyether-modified silicone defoamer consumption foam performance, centrifugal stability, better thermal stability and water-dispersibility. It has a good effect at different temperature in the system.