A chemical titration method for the determination of the average substitution degree of methylated β-cyclodextrin was presented. The method was based on the quantitative reaction of methylated β-cyclodextrin with hydroiodic acid, bromine, and potassium iodide in turn. 借助甲基β环糊精依次与氢碘酸、溴及碘化钾的定量化学反应关系,设计了测定甲基β环糊精平均取代度n值的一种化学滴定法,并根据滴定原理探讨了计算n值的方程式。