Liver function tests can diagnose diseases such as acute liver injury, chronic liver injury and cirrhosis. 1. Acute liver injury: it mainly includes acute viral hepatitis and acute ischemic liver injury. Its main laboratory test change is characterized by significant elevation of aminotransferases, AST＞200U/L, ALT＞300U/L, usually exceeding the upper limit of normal reference range by more than 8 times. 2. Chronic liver injury: mainly including chronic viral hepatitis, autoimmune hepatitis, Wilson’s disease, hemoglobin deposition disease. In chronic liver injury, serum aminotransferase activity is mildly elevated, usually less than 4 times of the upper limit of its normal reference range, and the elevation of serum ALT is greater than the elevation of AST in most patients with chronic liver injury. 3. Cirrhosis: In cirrhosis, the ratio of serum ALT/AST is often <1, and the higher the degree of fibrosis, the lower the ratio. In addition, in cirrhosis, platelet reduction, decreased synthesis of serum proteins, increased globulin and prolonged PT.