Abstract: The curves of several dependent functions of extension evaluation are plotted.The features and application occasions for these dependent functions are discussed.One simple corollary is proposed and briefly proved.Some inaccurate ideas and des-criptions about extension theory in some papers are pointed out.The similarities and differences between variable fuzzy method and extension method are analyzed.The comparison of physical geography boundary division results for Fujian Province using these two methods with the maximum points of the dependent function and the relative difference function at four different special positions is given at last.