Continuous stirred bioelectrochemical system (CSBES), consisting of anaerobic digestion reaction zone (ADRZ) and bioelectrochemical reaction zone (BERZ), was constructed to investigate the ammonia inhibitory effects on the performance of electricity generation and wastewater treatment. Continuous experiments were conducted with ammonia concentration ranging from 300 mg/L to 1200 mg/L. As the ammonia concentration increasing from 300 mg/L to 900 mg/L, both of the maximum power densities and the COD removal increased. When the ammonia concentration reached to 1200 mg/L, the maximum power densities of the four cells decreased by 55.7%, 58.9%, 58.0% and 60.6% in comparison with that under ammonia concentration of 900 mg/L. The COD removal reduced to 71.2 ± 1.4%, leading to COD concentration in the effluent increased to 1758 ± 93 mg/L. Electrochemical measurements revealed that the deterioration of anode performance caused the reduction of power generation. The conductivity control experiment showed that the toxic effects of high ammonia concentration on exoelectrogens caused performance deterioration of the CSBES. The threshold ammonia concentration that triggered the inhibition effect on exoelectrogens in CSBES was 1200 mg/L, and the anaerobic consortium in ADRZ could tolerant to higher ammonia concentration than the exoelectrogens in BERZ.