The leaves of 62 xerophytes in northwest China were investigated with structure observation under light microscope,the compute of biology statistics and fuzzy cluster analysis.The diversity of xerophyte′s ecological adaptation is discussed.The main experimental results are reported as follows. (1)Xerophytes may be divided into 7 types:normal,twoside plisade,ring palisade,total palisade,irregular,folding and no mesophyll in accordance with mesophyll structure and cell arrangement. (2)The evolution tren...