Objective To analyze the differences in plasma bile acid (BA) concentrations and BA profile in colorectal cancer patients with varying metastatic conditions, and to evaluate the clinical value of plasma BA ratio combined with tumor markers in diagnosing colorectal cancer liver metastasis (CRC-LM). Methods A total of 163 patients diagnosed with colorectal cancer between Apr. 2021 and Jan. 2022 were enrolled from Shuguang Hospital of Shanghai University of Traditional Chinese Medicine. They were categorized into 2 groups: non-metastatic group (CRC-NM group, n＝82) and CRC-LM group (n＝81). Clinical data and peripheral blood samples were collected from all the participants, the quality of life was evaluated using Karnofsky performance status (KPS) score, the levels of total bile acid (TBA) and tumor markers (carcinoembryonic antigen［CEA］ and carbohydrate antigen 125［CA125］) were examined, and the plasma concentrations of 15 BAs were detected using high-performance liquid chromatography/tandem mass spectrometry. The BA concentrations and BA profile were compared between the 2 groups. Additionally, receiver operating characteristic curve was generated to evaluate the efficacy of the BA ratio combined with tumor markers in diagnosing CRC-LM. Results No significant difference was found in age, gender, tumor location, degree of pathological differentiation, or KPS score between the 2 groups (all P＞0.05). Patients with CRC-LM had significantly higher concentrations of TBA, CEA and CA125 compared to those without metastasis (all P＜0.001). Additionally, the concentrations of glycocholic acid, deoxycholic acid, taurodeoxycholic acid, glycodeoxycholic acid, glycoursodeoxycholic acid, lithocholic acid and glycolithocholic acid in patients with CRC-LM were significantly higher compared to patients without metastasis (all P＜0.05). Furthermore, the plasma concentration of secondary bile acid (SBA) in CRC-LM patients was significantly higher than that in non-metastatic patients (P＜0.001), and the ratio of SBA to primary bile acid (PBA) was also significantly higher in CRC-LM patients (P＜0.001). Combination of SBA/PBA ratio with CEA and CA125 yielded a sensitivity of 71.60%, a specificity of 80.49%, and an area under curve of 0.820 (95% confidence interval 0.754 to 0.885, P＜0.001). Conclusion The plasma BA concentration is elevated in patients with CRC-LM, and the BA profile is notably different from that of patients without metastasis. The SBA/PBA ratio combined with CEA and CA125 demonstrates a great value for diagnosing CRC-LM.