Objective To develop a method for determination of 18 organophosphorous and carbamate pesticides in human plasma by UPLC-MS/MS. Methods Following deproteinization by acetonitrile, an aliquot of the biological sample was injected into a C18 column(1.7μm 2.1×50mm) using 5mmol/L Ammonium acetate-methanol as the mobile phase with the flow rate of 0.3mL/min, the injection volume was 10μL. Electro spray ionization(ESI) Indicators source was applied and operated in positive ion mode, and multiple reaction monitoring(MRM) mode was used to quantify. Results The limits of detection(LODs) in human plasma ranged from 0.1 to 40ng/mL, and the limits of quantitation(LOQs) ranged from 0.5 to 50ng/mL. An excellent linearity was observed for these LOQs up to 50ng/mL. The average extraction recoveries were with in 64.3%~111.9%, relative standard deviation(RSD) is 3.9%~10.3%. Conclusion This method is specific, sensitive and accurate, and can be used to detect pesticides in forensic.