In this study,non-target metabolomics methods were used to study the metabonomic differences between trimethoprim-sulfamethoxazole (SXT) -resistant and sensitive strains of Listeria monocytogenes.Ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) was used to obtain the intracellular metabolic profile information of the strains contained by SXT-resistant and sensitive strains.OPLS-DA discriminant models were established to illustrate the metabonomics differences,then the number and type of different compounds were qualitatived and their regulatory expression in metabolic pathways were analyzed.The results showed that there were significant differences in the metabolic characteristics of drug-resistant strains and sensitive strains.A total of 21 compounds that contributed significantly to the classification were identified,mainly amino acids and nucleotides.Differential metabolites are mainly involved in the pathways of amino acid metabolism,carbohydrate metabolism and nucleotide metabolism.The expression changes of adenosine,tryptophan and leucine in two significantly different metabolic pathways indicate that the synthesis of peptides and proteins in the cell has been blocked and the cell oxidative stress has increased after the strain is affected by the compound trimethoprim.The metabolism of glycerophospholipids indicated that the cell regulation of transport,protein function,and signal transduction were severely affected by the strains being affected by the SXT.The study clarified the reasons for the formation of the drug resistance of the strains affected by the SXT,and provided help for the search for drug targets and intervention in the prevention and control of strains.