A method was developed for the determination of low-ring polycyclic aromatic hydrocarbons(PAHs) and their derivatives in groundwater by liquid-liquid extraction(LLE) followed by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry(GC×GC-TOF MS).Compared with solid phase extraction(SPE),liquid-liquid extraction(LLE) shows higher extraction recoveries for samples, thus LLE was selected as the sample pretreatment method. The optimized results showed that the method has a good linear range of 0.1-1000μg/L with the correlation coefficients(r) higher than 0.99 for most of the targets, except for 1,2,3,4-tetrahydronaphthalene(r=0.9872) and biphenyl(r=0.9899).The spiked recoveries of the targets ranged from 63.3% to 111%with relative standard deviations less than 9.5%(RSD, n=6), except for quinoline(RSD，24.9%),and the detection limits ranged from 1.63ng/L to 14.7ng/L.The method was applied in the determination of low-ring PAHs and their derivatives in real groundwater samples from Hebei province, and the pollutants in two-thirds of samples were detected with the maximum concentration of 353ng/L.