Aimed at Pottiaceae difficult to classify and controversial to taxonomy of most genera in this family,we chose 4 subfamilies,11 genera,13 species representative of Pottiaceae in China,then observed and compared the morphology,size,number,density and formation of the leaf cell papillae and mammillae under light microscope (LM).The results show Pottiaceae papillae and mammillae mainly have three types:rounded papillae,bifid papillae and mammillae.To different species,there are more or less differences in the morphological characters and distribution of the two structures.Based on the above results,and through comparing the descriptions of the 13 species papillae and mammillae in different literatures,we corrected the descriptions errors and provided the best-fit way to distinguish the two structures.Besides,to Pottiaceae,we think papillae and mammillae are stable characters and have important and auxiliary function for classify the Pottiaceae species among the same genus and different genera.