Gas chromatography determination of polyhydroxyalkanoates has been common; however,the pretreatment steps are often complex,and gas chromatography operation conditions are not given in detail.In this study,gas chromatography is used for analyzing PHB,PHV and PH2MV,three majors of PHAs in activated sludge.The sample was centrifuged at a speed of 4000 r/min for the separation of floc and supernatant,freezen,and dried for 12 h in vacuum freezing drier; and then transferred to the fridge for freezing to ice and drying for 12 h in vacuum freezing drier; then chloroform and a simple composition digestion solution including methanol,sulfuric acid and benzoic acid was added; digested at 105 ℃ for 6 h; cooled to room temperature,the lower solution of the result can be used for analyzing.Samples were analyzed by gas chromatography with FID detector and auto sampler; the standard curve of standard material shows an excellent linear relationship with correlation coefficients larger than 0.99 ; the relative standard deviation(RSD)of sludge samples is less than 1 ％.The recovery rates of each sample are between 95％-105％.The GC analysis time of each PHA sample is shorter than 10 minutes.