Abstract: According to the QuEChERS pretreatment in GB 23200.113—2018 national food safety standard-Determination of 208 pesticides and metabolites residues in foods of plant origin-Gas chromatography-tandem mass spectrometry method, a mathematical model was established for the determination of 15 pesticides and metabolites residues in tea, cabbage and apple by gas chromatography-tandem mass spectrometry (GC-MS/MS), and the uncertainty was evaluated by analyzing the main sources of uncertainty. The results indicate that the values of expanded uncertainty caused by working curve and recovery are larger than the preparation process of standard solution and sample, however, repeatability and instrument caused minimum expanded uncertainty, and there are differences among the uncertainty caused by working curve, recovery and repeatability for different matrix. Mismatched matrix working curves could enhance or inhibit the matrix effects of some pesticides. This study not only applies to the uncertainty evaluation of pesticides and metabolites residues in foods of plant origin by GC-MS/MS but also provides a scientific and reliable reference for the accuracy of pesticide residue data.