Provided herein is a straightforward and efficient method for covalently attaching a polyethylene glycol polymer to docetaxel. The method involves, among other things, a step of reacting docetaxel with a polyethylene glycol polymer comprising a functional group reactive with a hydroxyl group within docetaxel in the presence of a coupling reagent and DPTS. The result of the reacting step is the formation of a polyethylene glycol-docetaxel conjugate having a single polyethylene glycol covalently attached, via an ester linkage, to the hydroxyl group within docetaxel.본 발명은 폴리에틸렌 글리콜 중합체를 활성제에 공유 결합시키기 위한 간단하고, 효과적인 방법에 관한 것이다.