Abstract: An advanced easy-carrying mass spectrograph (Model JLUMS-T02) with head-space sampling technique was used in the rapid determination of residual benzene hamologues in plastics for making food packing bags.Conditions of mass spectrometry were studied and optimized.Linear relationships between the base peak heights and the concentrations of benzene,toluene and xylene were obtained in the ranges of 0.29-29.36,0.29-28.87 and 0.29-28.67 μg·L-1 respectively,with detection limits of 0.017 μg·L-1 (for benzene),0.004 μg·L-1 (for toluene) and 0.009 μg·L-1 (for xylene).Precision and recovery of the method were tested giving values of RSD′s (n=5) less than 3.5% and recoveries in the range of 91.0%-103.6%.