Abstract: To compare the compositional differences among hydrothermal liquefaction products of various straw types, this study systematically analyzed the metabolite composition and variations in hydrothermal liquefaction liquids from tobacco, pepper, and corn straws using metabolomics methods. The results indicated that tobacco straw exhibited the highest degradation rate (43.25%) under hydrothermal conditions, along with the highest soluble protein and total sugar contents. Metabolomic analysis identified 2,559 metabolites across 11 categories, with hydrothermal liquefaction liquids of the tobacco straw showing significant enrichment of lipid and organic acid metabolites. Differential metabolites included anatabine (a nicotine-derived alkaloid unique to tobacco) and various lipid signaling molecules such as prostaglandins. KEGG pathway enrichment analysis revealed that the differential metabolites were primarily associated with energy metabolism, amino acid metabolism, alkaloid biosynthesis, and arachidonic acid metabolism pathways, highlighting the characteristics and advantages of tobacco straw in energy conversion and carbon fixation. This study elucidates the unique features and value of tobacco straw hydrothermal liquefaction products, providing a scientific basis for the high-value utilization of tobacco straw resources.