(1) functions of active ingredients: breaking and defoaming, reducing surface tension: representative: silicone oil, polyether, higher alcohols, etc. (2) effect of emulsifier: the active ingredients are dispersed into small particles, which are easy to disperse in water and have better anti-foaming and anti-foaming effects. Representative products: nonane (octyl) phenol polyoxyethylene ether, soap salt, op series, twain series, spang series, etc. (3) carrier function: it is conducive to the combination of carrier and foaming system, which can be easily dispersed into foaming system. When the two are combined, the surface tension is low, which is conducive to bubble suppression, and the cost can be reduced. Representative: solvents other than water, such as aliphatic hydrocarbons, aromatic hydrocarbons, oxygen-containing solvents, etc. Representative: * dispersant: hydrophobic silica, etc.; * viscosifier: CMC, polyethylene ether, etc.