Soil cation exchange capacity (CEC) has become a concern in the world for its importance in soil fertility and pollution. Characteristics and impact factors of CECs of yellow earth, yellow-brown earth, paddy soil, purple soil, fluvo-aquic soil and calcareous soil in the western margin of Sichuan Basin were investigated and compared in this study. The results showed that CECs were significantly lower in yellow earth, paddy soil and purple soil than in yellow-brown earth(P<0.05), but significantly higher than in fluvo-aquic soil(P<0.05). Soil CEC was significantly negatively correlated with mean annual temperatures, >0℃ and >10℃ cumulative temperatures(P<0.01), while showed quadratic function relation with precipitation and humidity index(P<0.01). CECs were higher in the mountain soils than in the plain and hill soils (P < 0.05), and soil CEC was significantly positively correlated with altitudes(P<0.01). CEC was higher in soils derived from glacial till than in soils derived from river alluvium and purple siltstone(P<0.05). The result of principal component analysis illustrated that temperature and precipitation of climate factors were the determinant for soil CEC in the study region.