Lubricating oil defoamer by containing special modified polyether raw materials through a special process compound, easy to dissolve in water, especially suitable for high temperature, strong acid and alkali, high shear force, high pressure conditions, continuous maintenance of defoaming, foam inhibition. With high temperature resistance, acid and alkali resistance, no floating, no oil floating; can be widely used in a wide range of temperature for a variety of harsh systems of foam elimination and inhibition. 1, Strong defoaming, foam inhibition, low dosage, does not affect the basic nature of the foaming system. 2,Good diffusivity and permeability, compatible with oil and cutting fluid. 3, Good heat resistance, chemical stability, non-corrosive, non-toxic, no adverse side effects, non-combustible, non-explosive. 4,It can be used in acid, alkali, salt, electrolyte and hard water.