Bilirubin is an endogenous substance produced by the body’s metabolism and is mainly produced by the breakdown of hemoglobin under physiological conditions. Total bilirubin includes both conjugated and unconjugated bilirubin forms. The degree of jaundice and its evolution can be judged according to the increase in total bilirubin. When elevated bilirubin is present, a person’s skin, sclera, and urine will show varying degrees of yellow changes. The normal value of total bilirubin in adults should be between 3.4 and 17.1 μmol/l. If the total bilirubin is between 17.2-34.2μmol/l, it is occult jaundice or subclinical jaundice; if the total bilirubin is between 34.2-171μmol/l it is mild jaundice; 171-342μmol/l is moderate jaundice; and greater than 342μmol/l, it should be severe jaundice. And the cause of jaundice can be inferred from the degree of jaundice, for example, hemolytic jaundice is usually less than 85.5 μmol/l, while hepatocellular jaundice is between 17.1 and 171 μmol/l. Total bilirubin, its main diagnostic significance is to determine the presence of liver disease or the occurrence of biliary disease, although of course hemolytic jaundice can also represent the presence of hematologic disease. In case of elevated total bilirubin, high attention should be paid to diseases caused by liver diseases such as chronic hepatitis, liver cirrhosis, liver tumors, etc., as well as diseases causing bile duct obstruction such as bile duct cancer and bile duct stones, etc. Therefore, if a patient has elevated total bilirubin, high attention should be paid to the occurrence of these diseases and active treatment should be provided.