Liver function tests usually reflect the physiological functions of the liver in the body and are used to detect the severity of liver diseases, including relevant indicators reflecting the metabolic function status of the liver and relevant indicators reflecting liver damage. 1.Protein metabolic function test: By detecting the relative content of plasma protein and protein fractions (protein electrophoresis), coagulation factor content and blood ammonia concentration, we can understand whether there is chronic damage to liver cells and the severity of the damage. 2, lipid metabolism function examination: when there is liver disease can lead to abnormal lipid metabolism. The examination mainly includes serum cholesterol and cholesterol ester measurement and obstructive lipoprotein X measurement. 3.Bilirubin metabolism examination: clinically, through the detection of serum total bilirubin, conjugated bilirubin, non-conjugated bilirubin, urinary bilirubin and urobilinogen, to diagnose the presence of hemolysis and determine the functional status of the liver and biliary system in bile pigment metabolism. 4.Bile acid metabolism test: Bile acid measurement can reflect the synthesis, uptake and secretion function of hepatocytes, and is related to the excretion function of biliary tract. It has higher sensitivity and specificity than other indicators for the diagnosis of hepatobiliary system diseases. Bile acid can be measured in fasting or 2 hours after meal, the latter is more sensitive. 5, uptake, excretion function test: when the liver function is impaired and liver blood flow is reduced, the excretion function of substances in vitro and in vivo will be reduced, so exogenous administration of artificial color (dye), drugs to detect liver excretion function is one of the frequently applied liver function test methods. Clinically, intravenous indocyanine green, lidocaine or sodium sulfobromophthalein are often used to understand the uptake and excretion function of the liver. 6.Serum enzyme and isoenzyme examination: liver is the organ containing the most abundant enzymes in human body. Changes in enzyme activity in the serum can reflect the pathological state of the liver and is one of the most active areas of laboratory examination for liver disease. Only after fully understanding the various common laboratory indicators of liver diseases can clinicians make reasonable use of experimental diagnostic indicators for diagnosis, differential diagnosis disease course monitoring and prognosis judgment of various liver diseases.