Abstract: An integrated cycling bioreactor with gas lift and microporrus aeration was used for the treatment of ABS resin wastewater. When the hydraulic retention time of the reactor was 24 h and the influent COD_Cr was 800-1 000 mg/L, the effluent COD_Cr was less than 80 mg/L. COD_Cr removal efficiency was higher than 88% and organic nitrogen removal efficiency higher than 99% by the single reactor. When the influent alkalinity was 300-450 mg/L (as CaCO₃), the pH of the mixed liquid in the reactor could remain at 6.7-7.5, and the effluent NH₃-N was less than 5 mg/L. The treatment load of the reactor was significantly higher than that of the traditional process. GC-MS and three-dimensional fluorescence spectrum analyses indicated that organic nitrile and aromatic organics could be efficiently removed from ABS resin wastewater.