Abstract: Due to stable and easy characteristics for operation , sequencing batch reactor sequencing batch reactor (SBR) activated sludge system has been widely used to treat various wastewater. The effects on removal of Pb^2%2Band COD from wastewater with different concentrations of Pb^2%2B (3, 5, and 10 mg/L) were explored in the SBR activated sludge system under long-term operation condition, and impact factors, adsorption kinetics and mechanism were also analyzed. Results showed that the removal rate of Pb^2%2B in the SBR activated sludge system reached stably 98~100% when the concentration of Pb^2%2B was 3 and 5 mg/L, while Pb^2%2B removal rate decreased to 90% when the concentration of Pb^2%2B was 10 mg/L in the SBR activated sludge system where 357.29 mg Pb^2%2B was accumulated at the later operation stage, suggesting the effect of Pb^2%2B accumulation on Pb^2%2B removal rate. The removal rate of COD was found to remain between 90~99% in the SBR system with different concentrations of Pb^2%2B. The optimal pH and temperature were 4~7 and 25 ℃, respectively. Under long-term operation process, MLSS decreased first and then recovered in the various Pb^2%2B containing SBR system, where microbial diversity and species richness reduced obviously, but Pb^2%2B resistant microorganisms were screened out. The pseudo-second-order kinetic model, FTIR and EDS analyses indicated that the adsorption mechanism of Pb^2%2B by activated sludge was mainly chemical adsorption, such as surface organic complexation and ion exchange.