Objective To develop a method for determination of 13 kinds of bile acid in healthy people and patients with pri-mary liver cancer by HPLC-MS.Methods Acetonitrile was used to precipitate protein in plasma samples .The separation was per-formed on a SHISEIDO MG C18 reverse phase column (3.0 mm ×100 mm,3μm).The mobile phase were acetonitrile and water (con-taining 0.1%formic acid and 0.5%ammonia), gradient elution.The flow rate was 0.4 ml/min, the temperature of column was 25℃and the injection volume was 5 μl.Electrospray ion source (ESI) and selected ion mode (SIM) were applied for quantitative analysis under negative ion mode .Results The calibration curves of 13 kinds of bile acids were linear in the range of 3.3-4 400 ng/ml, intra-day and inter-day precision results were all less than 7%, the average recovery were 82.67%-109.75%.The result showed that the content of conjugated bile acid increased in the plasma of patients with primary liver cancer compared with the healthy control group , especially in TUDCA, TCDCA, TCA, GCA and GCDCA.Conclusion The LC -MS method was sensitive and selective which could be suitable for determination of bile acid in healthy people and patients with primary liver cancer .The study laid a foundation for the me-tabolism of bile acid in vivo and the clinical diagnosis and treatment of patients with hepatocellular carcinoma .