Abstract: Activated sludge produced in wastewater anaerobic-aerobic treatment process contained a large number of Zoogloea. The formation of Zoogloea was related to the accumulation of intercellular Polyhydroalkanoates (PHA) of these microorganisms. So it is possible to produce PHA from activated sludge. In this work, the influence of the oxygen supply rate, attachment carbon source concentration and culture time to the accumulation of PHA were investigated. The molecular weight and monomer composition of PHA extracted from activated sludge were measured.