Abstract: Disclosed herein are uses of 4210 peptide as a marker in the diagnosis of liver cancer and cirrhosis. The 4210 Da peptide is differentially expressed in the serum samples of subjects with different hepatitis B-associated liver diseases, specifically, the expression level is the highest in patients with chronic hepatitis B, sequentially followed by patients with cirrhosis and hepatocellular carcinoma, and healthy controls and those with natural clearance of hepatitis B virus have the lowest expression level of the 4210 Da peptide. The invention provides a novel marker for assisting the diagnosis of a hepatitis B-associated liver disease, which can effectively assist the diagnosis of the hepatocellular carcinoma and the cirrhosis developed from chronic hepatitis B, benefiting the early diagnosis of hepatitis B-associated liver diseases.