Abstract: It ought to be established an unique site classification system of China according to the background of physical geography and the heterogeneity of regions in China.It has been known that there are the difference of heat on the latitude zonal variation as weel as the difference of humidity, geology and topography on the non-zonal variation in the natural condition of China. Especially, the difference of geology and topography is an important basis for site classification in mountainous regions.Site classification is the one of being controlled step by step, and its grades are determined by the different leading factors and are used for different objects. Afforestation division is carried out by the principle of environmental heterogeneith among regions on a large scale, namely, the difference of water, heat and huge topography as well as the difference of their secondary grades;Site classification is determined according to topography of large, medium and small site, nature of rock, quantitative and qualitative factors of soil.Site classification and afforestation division of China must be a system composed of five grade unites, they are:Afforestation region Afforestation province Site type district Site type group Site type