The invention discloses a method for preparing a novel organic 
silicon defoaming agent with excellent stability and defoaming ability. The traditional 
emulsion type defoaming agent is good in defoaming performance and low in stability or is high in stability and poor in defoaming performance. The method disclosed by the invention is characterized in that a certain amount of 
diethylene glycol monomethyl ether is added during preparation, the defect that the stability and defoaming performance of the traditional 
emulsion type defoaming agent are difficultly considered simultaneously is overcome, and the stability of the 
emulsion is greatly improved under the condition that excellent defoaming performance of the defoaming agent is guaranteed. According to the technical scheme, the organic 
silicon defoaming agent comprises the following four substances in percentage by 
mass: 10-20 percent of 
silicone cream, 3-5 percent of a composite emulsifier, 0.6-1 percent of CMC-HV and 2-5 percent of 
diethylene glycol monomethyl ether, wherein the composite emulsifier comprises 57-72 percent of peregal and 28-43 percent of 
fatty alcohol, and the HLB value is 9-12. The preparation method comprises the following steps: adding the four substances into a reactor, heating, uniformly stirring, and cooling to 
room temperature; and finally, and emulsifying at a certain rotating speed for 5 minutes by virtue of a high-shear emulsifying 
machine while adding water, thereby obtaining the defoaming agent.