Abstract: After 2 cigarette filters weighted were soaked with water of 20 mL, ethanol of 20 mL and 10.0 g·L^-1 internal standard solution of 50 μL were added and the mixture was extracted ultrasonically for 30 min. The supernatant of 2 mL was extracted by n-hexane of 5 mL.18 phthalate esters in the above solution were determined by gas chromatography-tandem mass spectrometry (GC-MS/MS), and the internal standard method was adopted for quantification. EI and MRM mode were adopted in MS analysis. Linear ranges of 18 phthalate esters were all 0.20-10 mg·L^-1, with detection limits (3S/N) ranged from 0.03 mg·kg^-1 to 0.50 mg·kg^-1. Test for recovery was made by standard addition method, giving results in the range of 86.8%-107%, with RSDs (n=6) all less than 7.0%.