Abstract: An analytical method for the determination of 45 organophosphorus pesticide residues in tea has been established by gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS). The rehydrated samples were extracted with acetonitrile and purified by Cleanert TPT SPE cartridge, eluted with V(acetonitrile) : V(toluene) = 3 : 1. The target compounds were detected by GC-MS/MS, and quantified by matrix matching external standard method. The effect of water addition on the extraction efficiency of organophosphorus pesticides in tea was discussed in detail. The calibration curves for 45 organophosphorus pesticides showed good linearity in their own ranges with correlation coefficients higher than 0.993.The limits of detection and the limits of quantitation of organophosphorus pesticide residues in tea were in the range of 0.001-0.01 mg/kg and 0.002-0.02 mg/kg, respectively.The average recoveries at spiked levels of 0.05, 0.5, 5 mg/kg ranged from 71% to 102% with relative standard deviations < 9.4%.