Abstract: The content of characteristic pollutants,including methyl tertiary butyl ether,benzene,toluene,ethyl benzene,p-xylene,m-xylene,o-xylene,and naphthalene,in the groundwater of gas stations were determined by Purge and Trap-GC/MS. The water sample was treated by a purge-trap concentrator and then separated on a HP-5MS capillary column. EI and full scan were adopted in MS. Fluorobenzene and 1,2-dichlorobenzene-D4 were used as internal standards for quantification. The linear relationship between the peak area and the mass concentration of the seven compounds was in a certain range,with detection limits in the range of 0.1-0.4 μg·L-1. The recovery rates measured by standard addition method were in the range of 91.0%-105%,with RSD in the range of 1.1%-3.9%