Landfill leachate was treated by A/O-coagulation-BDD combined processes, and the operation parameters were optimized. The optimal HRT and sludge recirculation ratio was 10.7 days and 3.5 for A/O treatment process. Reaction pH and optimal dose of ferric chloride coagulation treatment was 5.5 and 0.4 g/L. The current density and A/V ratio (anode area/reaction volum) for best performance of BDD was 60 mA/cm² and 4 m^-1. COD_Cr concentration in raw leachte and final effluent were 13375 mg/L and 60 mg/L, with the removal efficiency of 99.5%. TOC concentration before and after treatment by combined treatment process were 6893 mg/L and 12 mg/L, with the removal efficiency of 99.8%. Ammonia nitrogen was completely removed by the combined treatment processes from 1889 mg/L to 0 mg/L. The contribution of A/O, coagulation, and BDD was 59.0%, 32.9%, and 7.6% for COD_Cr removal of total COD_Cr, was 50.5%, 46.1%, and 13.2% for TOC removal, was 84.3%, 2.5%, and 3.2% for ammonia nitrogen removal, respectively.