Organic silicon defoaming agent capable of being used for water-based coating material and preparation method thereof

The invention relates to an organic silicon defoaming agent for a water-based coating material and a preparation method thereof. The preparation method comprises the following steps: (1) synthesizing isomeric alcohol ether terminated allyl polyether; (2) synthesizing end group isomeric alcohol ether terminated polyether modified silicone oil; (3) preparing silicon paste; and (4) preparing the defoaming agent. According to the invention, end group isomeric alcohol ether terminated polyether modified polysiloxane with a symmetrical structure is used, a hydrophilic eo chain segment, a hydrophobic po chain segment and an isomeric macromolecular alkyl alcohol ether group are simultaneously introduced to the end group of a polysiloxane chain, and the hydrophilic and hydrophobic properties of the polymer can be effectively adjusted by controlling the ratio of eo to po, so that better defoaming performance is realized; and the organic silicon defoaming agent disclosed by the invention has the advantages of easily ava