Abstract: The characteristics of matured aerobic granular sludge were studied using synthetic wastewater in two sequencing batch reactors (SBRs) with glucose (in R₁ reactor) and acetate (in R₂ reactor) as culture carbon sources respectively. The results of 102 days' operation revealed that in R₁ the size distribution displayed a wide range of 0.1～2.2 mm, spheral bacteria were the main microorganisms, oxygen uptake rate (OUR) and specific oxygen uptake rate　(SOUR) were1.184 mg/(L·min) and0.838 mg/(g·min), respectively, while in R₂ the size distribution had asmall rang of 0.1～1.0　mm, bacillius and spheral bacteria were the dominant microorganisms, OUR and SOUR were 0.944 mg/(L·min) and 0.825 mg/(g·min), respectively. In both reactors the COD_Cr removal efficiency was up to 95%～98% even with the COD_Cr load from 600 to 1　200　mg/L.