Abstract: The gas chromatography-tandem mass spectrometry(GC-MS/MS) multiple reaction monitoring(MRM) method was developed for the determination of seven kinds of BTEX(benzene, toluene, ethylbenzene, p-xylene, m-xylene, o-xylene and styrene) and internal standard fluorobenzene. This method used the product ion scanning mode to screen the qualitative and quantitative product ions of BTEX. Then collision energy for ion pairs was optimized to obtain high abundance and characteristic product ions. This method can be used for qualitative and quantitative analysis of BTEX more accurately because of its high sensitivity and stability. So it can be applied to the determination of BTEX residues in samples with complicate base.