According to the causes吐formation and properties of Quaternary red clay and their influences on red earths developed on it in the hilly regions of central subtropical China, the soils are distinguished into four families, i.e. siferryc residual red earths, siferric red earths, siferric plinthie red earths and siferric gravel red earth. The principles for distingushing the red earths in the category of soil species suggested by the eauthor are as follows:(1)in a given family with same pattern of solum stracture, the soil species are distinguished according to the fertility level of surface soil;(2) the soils with different patterns of solum structure are distinguished in different soil apecies in spite of soil fertility;(3) for cultivated soils, the soil species are distinguish according to the development deb}ree of surface and subsurface mil horizons resulting from fertilization and management of the soil. The association patterns of red earths being generally found in hilly regions of central China a} as follows:(1) weakly Proded pattern with all horizons overlaped, (2) weakly eroded,pattarn with residual catena, (3) strongly eroded cumulative pattern with apposite distributive order on the slope,(4) patch-like pattern with stronge hgdratian of iron oxides on gentle slopes, (5) strongly eroded gully-like pattern, (6) lithological symmetrical distributive pattern with hombgenous parent material, (7) lithological symmetrical distributive pattern with heterogemeous parent materials, (8) litholoaical belt-like covering pattern with heterogeneous parent materials, (9) eroded-annular distributive pattern.