Objective:To study the metabonomics of coix seed oil intervention on tumor growth in tripe negative breast cancer 4T1-bearing mice based on LC-MS. MethodsOrthotopic xenograft of 4T1 was established and randomly divided into control group, model group and coix seed oil administration group (7.5 mL/kg/d of Coix seed oil was given by gavage). After 14 days of administration, the mice in each group were executed to take tumor tissue and serum. HPLC-LTQ-Orbitrap Elite LC/MS was used to detect metabolic changes in the serum of each group of mice and identify differential metabolites.  Results:Coix seed oil significantly inhibited the growth of 4T1 in vivo (P<0.05). The levels of serum metabolites in normal mice, model mice and mice treated with coix seed oil showed different distributions. By orthogonal partial least squares-discriminant analysis(OPLS-DA), the differential metabolite was selected by VIP values >1 among control group, the model group and the coix seed oil administration group (P<0.05). Compared with the normal group, 16 metabolites changed significantly in the model group, including pregnanetriol, LysoPC [18∶3 (9Z,12Z,15Z)],lysophosphatidylethanolamine [0∶0/22∶6 (4Z,7Z,10Z,13Z,16Z,19Z)], LysoPC [22∶5 (7Z,10Z,13Z,16Z,19Z)], LysoPC [22∶4 (7Z,10Z,13Z,16Z)], Pyruvic acid, 2,6-diamino-4-hydroxy-5-(N-methylformamido) pyrimidine, N-Acetyl-L-phenylalanine, Margaric acid, Oleic acid, Stearic acid, Arachidonic acid, Dihomo-gamma-linolenic acid, Retinyl acetate, 6-hydroxy-5-methoxyindole glucuronide, 1-stearoyl-sn-glycero-3-phosphoethanolamine, among which the metabolite N-Acetyl-L-phenylalanine increased, other metabolites decreased and these differential metabolites showed a significant correction trend after coix seed oil administration (P<0.05).  Conclusion:Coix seed oil may have an anti-tumor effect on mice bearing 4T1 tumor by regulating arachidonic acid metabolism, biosynthesis of unsaturated fatty acids, mutual conversion of pentose and glucuronic acid and pyruvate metabolism.