Abstract: A method combining dispersive solid phase extraction(DSPE), wherein multi-walled carbon nanotubes(MWCNTs) were used as adsorption material, with liquid chromatographytandem mass spectrometry(LC-MS/MS) was developed for simultaneously determining 114 pesticide residues in tobacco. The type and adding rate of MWCNTs were optimized by experiments, and the purification of samples was improved by Qu ECh ERS method. The results showed that: 1) It was more efficient using 5 mg MWCNTs of above 50 nm in external diameter than using N-Propylethane-1, 2-diamine(PSA) in sample purification. 2) The calibration curve presented good linearity(r² > 0.999). The average recoveries at spiked levels of 0.02, 0.05 and 0.20mg/kg ranged from 69% to 119% with the relative standard deviations of 1%-19%, and the LOQs of the method were in the range of 0.2-40.0 g/kg. The developed method is accurate, sensitive, convenient, and suitable.