Abstract: Speciation characteristics, influencing factors and effectiveness of As, Cd, Cr and Pb in four main types of soils (purplish soil, limestone soil, yellow soil and paddy soil) were investigated through analyzing total contents and fractions of heavy metals in soils in Yubei District, Chongqing. The results showed that fractions of heavy metals significantly varied among different types of soils. Cr and Pb were the main components of the residual in all kinds of soils. Cd was mainly ion-exchangeable and residual speciated in yellow soils and purplish soils, which counted for 37.44% and 29.97% of the total Cd contents, respectively. The contents of available speciation of heavy metals in soils was as follows:w (available As) and w (available Cr) were 0.04and 0.96mg/kg in purplish soil respectively, w (available Cd) 0.13and 0.09mg/kg in paddy and purplish soil respectively, w (available Pb) was 1.94mg/kg in yellow soil, which perhaps indicated a strong bio-effectiveness, when the bio-effectiveness of heavy metals in limestone-soil was lower. Available As and Cd significantly positively were correlated with total contents in main factors influencing on the chemical speciation and transformation process of heavy metals. However, there were significant negative correlations between available contents of Cd and Pb with pH, and between available Cr with soil organic matters. Available Cd, Cr, and Pb have a multivariate nonlinear logarithmic regressive relationship with total contents, pH and SOM in purplish soil. In conclusion, the equation can be used to effectively predict available contents of the heavy metals in the study area.