Abstract: In this study, 25 volatile organic pollutants, including halogenated hydrocarbons, benzene series compounds and chlorobenzenes in groundwater were qualitatively identified and quantitatively analyzed by gas chromatography-mass spectrometry with headspace sampling. The sample transfer mode, box temperature of sampler and shaking time in the sampling process were studied and optimized. The detection limits of the method for the pollutants were 0.03~0.13 μg/L and the average recoveries were 84.5％~127.2％ with the precision of 1.98%~11.59% RSD. The method has been successfully applied to the determination of 25 volatile organic pollutants in groundwater samples from national project of pollutant survey and evaluation in groundwater.