Abstract: A screening system was established for simultaneous detection of abused drugs in hair by GC/MS/MS. The results showed that tandem mass spectrometry (MS/MS) technique can effectively reduce the background due to complex matrixes by excluding all unwanted ions except the parent ion, and has advanages of high sensitivity of SIS and structural information of scan. The recoveries of 13 abused drugs range from 68 to 101%, with low limits of detection (0. 01-2ng/mL hair).