Laboratory batch experiments were carried out to study Pb sorption desorption by four soils typical of the Yangtze River Delta in China. Thermodynamic parameters, like K°, ΔG°, ΔH° and ΔS°, were used to explain mechanism of the sorption. Results show that under the conditions of the experiment (two temperature treatments, 25±0.5℃ and 35±0.5℃) Pb sorption and desorption displayed nonlinear curves that fitted the Freundlich isotherm. The sorption K_fvalues of the four soils followed an order of Lithic Ochri-Aquic Cambosols (3 816 dm³ kg^-1) > Endogleyic Feaccumulic Stagnic Anthrosols (1 984 dm³ kg^-1) > Typic Gleyic Stagnic Anthrosols (1 030 dm³ kg^-1) > Fe-accumulic Gleyic Stagnic Anthrosols (348 dm³ kg^-1). In soils with organic matter removed, Pb sorption capacity decreased, but desorption rate increased. The K and ΔS° values increased with temperature, while ΔG° values decreased with temperature. The negative values of ΔG° suggested that Pb sorption was a spontaneous process. The positive ΔH° values indicated that Pb sorption was an endothermic process. Chemical bonding force is the major force in Pb sorption by Endogleyic Fe-accumulic Stagnic Anthrosols, Typic Gleyic Stagnic Anthrosols and Lithic Ochri-Aquic Cambosols, and Van Der Waals Force and dipole bonding force in Feaccumulic Gleyic Stagnic Anthrosols. Apparent hysteresis in Pb sorption-desorption was observed and varied from soil to soil, and the higher the pH, calcium carbonate content and equilibrium concentration, the higher the hysteresis index, which may be attributed to the formation of inner-sphere Pb sorption complex (less reversible) and precipitation of lead carbonate.