Abstract: Objective:To evaluate the measurement uncertainty of organophosphorus pesticide residues in vegetables by gas chromatography and provide a reference for objective analysis of the reliability of multi-component pesticide residue detection results in vegetables.Methods:The whole process of determination of organophosphorus pesticide residues was analyzed based on the standard method of the second method in the first part of NY/T 761-2008.The uncertainty of the detection method was evaluated from five aspects:standard solution,sample preparation,repeatability,standard curve fitting and recovery rate.The source and value of uncertainty were confirmed. The synthetic standard uncertainty was synthesized. The extended uncertainty was calculated and the results were reported.Results:The content of 16 organophosphorus pesticides in vegetables were 0.100 mg/kg to 0.339 mg/kg,and the extended uncertainty was 0.016 mg/kg to 0.052 mg/kg(P=95%,k=2).Conclusion:The measurement uncertainty of organophosphorus pesticide residues in vegetables by gas chromatography was mainly derived from standard curve fitting,followed by recovery rate.By choosing appropriate concentration of standard solution to make standard curve,optimizing pretreatment method and quality control sample,the uncertainty can be reduced,and the accuracy and reliability of test results can be guaranteed.