A method of ultra high performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) was established for the simultaneous determination of 115 pesticides in blood.The blood sample and the extractant methanol were mixed at a volume ratio of 1∶5,vortexed for 2 min,centrifuged at 12 000 r/min for 10 min,and thesupernatant was taken for UPLC-MS/MS analysis.Scheduled multiple reaction monitoring in both electrospray ionization positive ion mode(ESI+) and negative ion mode(ESI-) were adopted in MS analysis.Results showed that there were good linear relationships for 115 target pesticides in the concentration range of 1-200 ng/mL with their correlation coefficients(r) larger than 0.99.The limits of detection(S/N≥3) were 0.2 ng/mL for 13% of the target pesticides and 0.1 ng/mL for the rest of pesticides.The limits of quantitation(S/N≥ 10) for all the target pesticides were 1 ng/mL.At the spiked levels of 10,50 and 100 ng/mL,the matrix effects of the method were between 81.8% and 115%.The recoveries for the target pesticides ranged from 80.4% to 109%,with intra-RSDs and inter-RSDs of 1.6%-11% and 1.9%-13%,respectively.The method was simple,rapid,sensitive and stable,and was suitable for the qualitative and quantitative analysis of multi pesticide in blood samples.