Abstract: Phthalate esters (PAEs) are the main organic pollutants in groundwater. The potential for using compound specific stable carbon isotopic ratios to trace the pollution source and process is presented in this paper. This method will provide reliable information for pollution control. The research results indicate that the physical changes during the sample pretreatment do not impact the mass fractionation of the compound specific stable carbon isotopic ratio. A method for the analysis of the compound specific stable carbon isotopic ratios of five PAEs, i.e. dimethyl phthalate (DMP), diethyl phthalate (DEP), dibuthyl phthalate (DBP), diisobuthyl phthalate (DIBP), and di-(2-ethylhexyl) phthalate (DEHP) by Gas Chromatography-Isotope Ratio Mass Spectrometers (GC-IRMS) is described. The stable carbon ratio of the PAEs before and after liquid-liquid extraction (LLE) was analyzed. The results show that the stable carbon ratio of the PAEs did not change significantly, which suggests that LLE is reliable as the pretreatment method for water samples for compound specific stable carbon isotopic analysis.