The effect of dissolved oxygen (DO) concentration on aerobic granular sludge (AGS) treatment on simulated municipal sewage was studied in SBR reactor. By changing the amount of aeration, the DO concentration in SBR reactor was controlled respectively in the range of 3 mg/L≤ρ（DO）＜4 mg/L, 2 mg/L≤ρ（DO）＜3 mg/L and 1 mg/L≤ρ（DO）＜2 mg/L. The concentrations of COD, NH {}_{\mathrm{4}}^{+} -N, NO {}_{\mathrm{3}}^{—} -N, NO {}_{\mathrm{2}}^{—} -N, TN and P in the effluent were detected. The results show that the removal rates of COD, NH {}_{\mathrm{4}}^{+} -N and P are affected little by the DO concentration, but the removal rate of TN is affected significantly. When 3 mg/L≤ρ（DO）＜4 mg/L, 2 mg/L≤ρ（DO）＜3 mg/L和1 mg/L≤ρ（DO）＜2 mg/L, the removal rate of TN is 62.14%, 71.81% and 82.11% respectively; when 1 mg/L≤ρ（DO）＜2 mg/L, the removal rate of TN reached the best for the AGS system and the system was stable. The average removal rates of COD, NH {}_{\mathrm{4}}^{+} -N and P were 90.43%, 96.97% and 76.00%, respectively.