Polyhydroxyalkanoates（PHAs）are environmentalfriendly biothermoplastics with the potential of wide applicationPHAs synthesis by activated sludge is costsaving and beneficial for waste recycleThe monomer composition and content of PHAs determine the physicochemical characteristics of the polymerBased on the technology of optimizing PHAs production，the process manipulation and biochemical metabolism for regulating the hydroxyvaleryl content in poly（3hydroxybutyrateco3hydroxyvalerat（PHBV）by activated sludge were summarizedLiterature review indicated that under aerobic condition the nature of carbon substrate was crucial to the final composition of PHBVGenerally，decrease of dissolved oxygen concentration（DO）led to hydroxyvaleryl [JP2]content enhancement，and variation of sludge source，pH and carbon to nitrogen and/or phosphorus ratio all tended to alter hydroxyvaleryl content.The effects of the above parameters on hydroxyvaleryl content were interrelated with each otherFurther research to regulate the composition of PHAs from activated sludge was forecasted.