Abstract:In the paper, the archinecture of leaves and their possible ecological significance of 82 dominant and common species from the semi-humid forest occurring in C.Yunnan were stu-died. The characters of 82 species were presented as follows: most species are with simple leaves, in which the serrate types are a little more than intergrifolius and the glabrous types are a little equal to trichomes, venation pinnate, secondary veins brochidodromous often with ascending arches and Joining super adjacent secondary and enclosed by 3 or 4 arches. The angles between main vein and secondary veins are acute, and the divergence of the angles is often nearly uniform; Tertiary veins most are reticulate. The areoles often develope perfectly and embedded veins almost are inconspicuous or absent.