A comparative analysis of the functional groups and surface structure of the Ca-bentonite (RB) and thiol-modified bentonite (TMB) were characterized by means of FTIR and SEM. The absorptive property of Pb2+ on TMB and RB and its influential factors was studied and the conditions for the adsorption were optimized by using FAAS method. Then the conditions for desorption of Pb2+ from the TMB by using simulated acid rain were studied and the contrast analysis of absorptive stability of Pb2+ on TMB and RB was given. The results showed that the adsorption rate of Pb2+ by TMB could reach more than 98%, when the initial Pb2+ concentration was 100 mg·L-1, the liquid-solid ratio was 5 g·L-1, pH was 6.0, KNO3 ionic strength was 0.1 mol·L-1 and adsorption period was 60min at 25 ℃. The saturated adsorption capacity of TMB was 67.27 mg·g-1; it’s much more than that of RB (9.667 mg·g-1). The adsorption of Pb2+ on TMB follows Langmuir and Freundlich isotherm models well. Desorption experiments of Pb2+ from TMB with simulated acid rain (pH 3.50) were done, and the desorption rate was 0. The results showed that TMB has a strong adsorption and fixation capacity for Pb2+; it is adapted to lead contaminated soil for chemical remediation.