Provided in the present invention is a device for diagnosing liver cancer. The device determines the level of a biomarker in a biological sample of a subject to be a diagnostic indicator, wherein the level of the biomarker is selected from the level of one or more of taurocholic acid, taurochenodeoxycholic acid, glycocholic acid, glycochenodeoxycholic acid, linolelaidic acid (C18:2n6t), maltotriose, maltose and/or lactose, α-linolenic acid, β-alanine, sebacic acid, 2-methylvaleric acid, valeric acid, isovaleric acid and hexanoic acid, and/or the ratio of secondary bile acid to primary bile acid, and/or the ratio of glycine-conjugated primary bile acid to taurine-conjugated primary bile acid, the primary bile acid being selected from cholic acid and chenodeoxycholic acid, and the secondary bile acid comprising deoxycholic acid, lithocholic acid and ursodeoxycholic acid. The diagnosis device of the present invention can be used for early diagnosis of liver cancer and liver cirrhosis, thereby buying time for patients and improving the clinical treatment effect.