Abstract: When preparing quaternary ammonium salt type active etherifying agent- epoxychloropropyl triethylammonium chloride with epichlorohydrin and trimethylamine, its synthesizing process is difficult to control, for trimethylamine is a kind of gas. For this reason, this paper investigates synthesizing quaternary ammonium salt type cationic etherifying agent- epoxychloropropyl triethylammonium chloride with liquid triethylamine substituting for gaseous trimethylamine. The effect of synthesizing conditions on the product yield is analyzed and the optimal process conditions are determined. The element content, epoxy value, melting point, and water solubility of the product are tested, and it is found that the product yield is up to 94.53%, epoxy value is 90.36％, and melting point is 138～140℃. It is considered that the quality of the product is good.The use of liquid triethylamine makes the reaction process easy to control, thus meeting the requirement commercial product by lot.