Via the survey of 250 plots, tree species diversity and community structure were discussed in the habitats of black- crested gibbons, Wuliang Mountain, Yunnan, China. The research showed that (1) 111 tree species from 33 families and 23 lianas from 18 families were recorded in all, in which dominant families included Lauraceae, Magnoliaceae, Fagaceae, Theaceae and Ericaceae; (2) two forest vegetation types existed in the study area: the semi-humid evergreen broad-leaved forest and mid-mountain humid evergreen broad-leaved forest; (3) the diversity index declined with the rising of elevation in each forest vegetation; however, the evenness index showed degressive trend only in semi-humid evergreen broad-leaved vegetation; (4) the age structure of six dominant species revealed that the tree layer in the study area would increase stably.