The genetic process of the soils on Hengshan Mt.in Hunan province are getting stronger with the increase of the altitude,and the vertical sequence of the soils from the mountain foot to the summit is in the order of red earth,mountain yellow earth and mountain meadow soil.This regularity is well reflected in the constituents of the clay minnrale of the soils.It was found that the quantity of kaolinite decreased and that of gibbsite increased with the increase of the altitude.however,hallaysite existed in almost all the soils,especially in layer B and C horizons.The weak-weathered clay minerala such as hydromica,hydrobiotite,and chlorite mainly exist in the soils on upper hart of the mountain.