The present paper deals with the characteristics of surface charge in zero point of charge (CPC) of certain soil colloids, and the problems of terms of the electrometric titration curves. Five soil colloids(<2u) separated from laterite, red earth, yellow brown earth, loess and black soil were used in the present study. The results obtained are summarized as follows: The magnitude of ZPC values of these samples was followed in the order of laterite (4.00),red earth (3.00), yellow brown earth (2.35),loess (2.25) and black soil (2.15). This sequence conformed to the soil zonality. The ZPC values were gradually reduced from south to north, and this tendency was related to the mineralogical composition and the content of organic matter of soils.