To solve some taxonomic problems of Theaceae, 13 leaf epidermal micromorphology characters of 20 species, which are from 2 subfamilies and 6 genera of Theaceae, were observed under light microscope and used for the cluster analysis and principal component analysis, providing reference to scientifical classification of Theaceae. The result illustrated that: (1) the 20 species was well distinguished by the 13 characters and different characters could be used to differentiate various ranks of taxonomic taxon, which showed allaround taxonomic value. (2) The cluster analysis and principle component analyses based on micromorphology characters divided the 20 species into 2 clades and 10 isolates, suggesting that the taxonomy system could well distinguish Theoideae and Ternstroemoideae, and mainly group species with close taxonomic status together, which preferably reflected the relationships between species. (3) This study offered evidence of leaf epidermal micromorphology for the independence of Sect. Luteoflora and supported the segregation of Camellia chungkingensis from Sect. Tuberculata Chang Tax. Besides, this study indicated that dividing Theoideae and Ternstroemoideae into 2 clades was logical, but the viewpoint that Ternstroemoideae and Pentaphylacaceae should be clustered together needs more proof.