This article analyses quantitatively the following five groups of variants of Chinese character included in《Modern Chinese Dictionary》“xihan 希罕—稀罕”、“xiqi 希奇—稀奇”、“xishao 希少—稀少”、“xishi 希世—稀世”and“xiyou 希有—稀有”,expounds the reasons of selecting different words and tells the function of the two words in different forms.