The performance of sequencing biofilm batch reactor (SBBR) under micro-aerobic condition for aniline-contaminated wastewater treatment was investigated in this study. Dissolved oxygen (DO) and aniline concentrations were selected as the operating variables to analyze, model, and optimize the process. In order to analyze the process, 5 dependent parameters, chemical oxygen demand (COD), aniline, ammonium, total nitrogen (TN), and total phosphorous (TP) removal as the process responses were studied. From the results, increase in DO concentration could promote the removal of COD, aniline, ammonium, and TN, while increase in aniline concentration has a slightly negative impact on the removal of pollutants. The optimum DO concentration was found to be 0.4-0.5 mg/L. The removal efficiencies for COD, aniline, ammonium, and TN at the optimum point (DO concentration 0.5 mg/L, aniline concentration 11 mg/L) were 95.84%, 100%, 75.72%, and 45.39%, respectively. The oxidative deamination was the main degradation method for aniline under micro-aerobic condition. Simultaneously nitrification-denitrification (SND) process performed under micro-aerobic condition and about 20%-40% nitrogen was removed by SND. Copyright © 2014 Editorial Department of Journal of Donghua University. All rights reserved