Abstract: According to the chemical analyses of both leaves from 63 species of plants and 25 species of timbers, the chemical characteristics of plants and different vegetation types in tropical forests and the contents of the major elements were studied with the applications of both principal component analysis and cluster analysis. From the view-point of chemistry, the regulations of structure, function and the space distribution of the tropical forests had been revealed. The percentage of element contents of both leaves and stems are as follows:C 45.13, SiO2 2.05, N1.68, K0.87, Ca0.47, Mg0.22, P0.08 and ash 5.87 are in leaves, C 48.44, N0.82, SiO2 0.59, K0.19, Ca 0.045, Mg 0.042, P0.013 and ash 2.104 are in stems. Their quantities in different forests in orders are semideciduous monsoon forest, evergreen monsoon forest, mountain rain forest and mossy forest. The types of phytochemistry of leaves were divided into five or six groups by both of the principal component analysis and cluster analysis. The conclusion of the research has an important academic value for the further study on the tropical forest ecosystem, providing basic background data.