Through the analyses of the changes of the free iron oxides, the ratio of free iron oxides to total Fe, soil CEC and IEP of soil colloids with the age of basalt, the surface chemical properties of six soils collected from Leizhou Peninsula and northern part of Hainan Island as related to soil pedogenesis were investigated. The results indicated that both the ratio of free iron oxides to total Fe and free iron oxides were significantly positively correlated with the age of basalt and the former was correlated with the age of basalt better, but total Fe of soils was not correlated with the age of basalt. Soil CEC decreased but IEP of soil colloids increased with the increase of the age of basalt. Further investigations suggested that the spatial pedogenesis played more important role on CEC and IEP of the soils than time factor, especially on soil IEP.