Abstract: Tribolium castaneum (T. castaneum) is a pest that poses an important threat to food and grain production worldwide. In recent years, botanical insecticides have been widely promoted, in which plant essential oils are considered potential candidates for developing green insecticides. The previous bioassay studies of our research group showed that Chamaecyparis obtusa (C. obtuse) essential oil had certain contact activity against T. castaneum, and the LD₅₀ was 52.54μg/adult. At three concentrations (0.41,1.62, and 2.83 uL/cm²), the repellent rates of C. obtusa essential oil against T. castaneum were all above 80% at 15, 30, 60, and 120 min, respectively, indicating that the repellent effect was strong. Meanwhile, the C. obtusa essential oil exhibited fumigant toxicity against T. castaneum with LC₅₀ values of 7.09 μg/L air.In this study, we used LC-MS non-targeted metabolomics technology to find that C. obtusa essential oil could affect the metabolic profile of T. castaneum. A total of 262 differential metabolites were identified (up-regulated: 230, down-regulated: 32), mainly involving amino acid related compounds, terpenoids, alkaloids, phenylpropanoids, polyketides, fatty acids related compounds and flavonoids. The VIP value analysis results of the control group and the C. obtusa essential oil treatment group showed that the VIP values of the five metabolites of prenyl cis-caffeate, glutamylleucylarginine, (S)-abscisic acid, 3-(8-hydroxyoctyl) phenol, and diethyl phthalate were higher, and the difference between the two samples was very significant. In addition, the KEGG pathway statistical analysis of the 262 differential metabolites screened showed that the differential metabolites in the control group and the essential oil treatment group were enriched into 35 pathways, involving 63 metabolites, mainly including amino acid metabolism, lipid metabolism, carbohydrate metabolism, cofactor and vitamin metabolism, signal transduction and other pathways. In summary, our results provide a basis for further understanding the potential metabolic effects of C. obtusa essential oil on T. castaneum and lay a foundation for developing more effective insect control strategies.