Abstract: Activated sludge developed by N+ ion beam injection was used to treat the coke-plant wastewater. The effects of activated sludge after domesticated and cultivated for 7 days and 12 days on coke-plant wastewater were studied. Results showed that the activated characteristics (MLSS, SV30 and SVI) and increasing rate of activated sludge were lowered compared with the control after N+ ion beam injection at intensity of 40×2.6×1013 N+/cm2～200× 2.6×1013 N+/cm2 but the effect was not significant. With the increasing of injection intensity from 40×2.6×1013 N+/cm2 to 200×2.6×1013 N+/cm2, increasing rate of activated sludge was decreased from -1.2 % to -2.0%. The corresponding removal efficiency of COD, NH3-N and phenolic compounds was also studied. The removal efficiency of COD and NH3-N of the activated sludge was increased after N+ ion beam injection, and its effect was enhanced with the injection intensity increasing from 40×2.6×1013 N+/cm2 to 160×2.6×1013 N+/cm2. The removal efficiency of phenolic compounds after the injection of activated sludge was increased significantly compared with the control, and the efficiency was the highest at the injection intensity of 160×2.6×1013 N+/cm2 as 99.76 %.