Chemical,mineralogical and micro-morphological properties of ferric allitic soils derived from basalts of different age in Leiahou Penisula and Hainan Island were studied.The results showed that,with the lapse of soil of forming age (Q₄-Q₁),primary minerals was getting less,the crystalinity of kaolinite became better,CEC deceased obviously,and so did the SiO₂/Al₂O₃,ratio of clay from Q₃ to Q₁,dithionitecitrate-extractable iron content increased gradually.