Abstract: To investigate the antitumor activity of shikonin against human colorectal cancer, the IC₅₀ value towards four different human colon cancer cells was detected by MTT assay. In addition, a SW620 xenograft model was established and both the tumor volume and tumor inhibitory rate were calculated to evaluate the antitumor activity of shikonin in vivo. To further explore the mechanism of shikonin, metabolomics combined with multivariate statistical analysis was performed to analyse the profile of metabolites in mouse serum. The results show that shikonin can significantly inhibit the proliferation of four different colon cancer cell lines and exerted a high antitumor activity in vivo. The tumor inhibitory rate at low dose and high dose were 38.35% and 42.16%, respectively. In addition, a total of 38 potential biomarkers related to the antitumor effects of shikonin were identified through metabolomics analysis, including tryptophan, proline and methionine. The study revealed that the mechanism was related to disordered amino acid metabolism in colon cancer, especially in tryptophan metabolism. Our study suggests that shikonin could exert an antitumor effect by regulating amino acid metabolism in colon cancer and provides a theoretical foundation for further exploration and the eventual clinical application of shikonin.