An investigation was made from north to south in china to study the soils’ chemical and clay mineral composition characteristics of < 2 μm clay.Four different types of soils (including brown earths,yellow-brown earths,red earths and humid-thermo ferralitic) developed from granite and gneiss were collected to find some clues to prove that climate conditions affect the composition of soil clay minerals in some degrees.The results showed that in brown earths,the clay minerals were mainly 2∶1 type.Illite was a ubiquitous mineral,followed by vermiculite and kaolinite.A small amount of montmorillonite did exist.In yellow-brown earths,kaolinite and vermiculite occupied the main part,followed by illite and montmorillonite.In red earths,vermiculite and montmorillonite disappeared and was substituted by kaolinite,illite and 1.4 nm intergrade minerals.1.4 nm intergrade minerals and vermiculite did not exist in the humid-thermo ferralitic.The content of kaolinite was up to 90%,followed by illite and a small amount of gibbsite.Annual average temperature and average rainfall were significantly positively correlated with kaolinite,and significantly negatively correlated with vermiculite and montmorillonite (P< 0.05).