Precautions before blood sampling mainly include: fasting before liver and kidney function, fasting blood glucose, etc. (blood routine, coagulation function, etc. do not need to fast); adequate rest, avoid staying up all night; avoid drinking alcohol, eat a light diet and so on. Clinical routine blood test items include blood routine, coagulation function, biochemistry and so on. Eating before blood sampling will cause the liver to secrete bile to participate in the digestive process, which may affect the results of liver function tests. Drinking a lot of water before the blood draw can lead to blood dilution, which may affect the accuracy of the blood test results. Staying up late, fatigue, alcohol consumption and other factors may lead to mild elevation of liver function indexes such as alanine aminotransferase and glutamyltranspeptidase; eating a large amount of greasy food, barbecue, etc. before blood sampling may affect the results of lipid analysis (included in the major biochemistry), so a light diet is required. Oral anticoagulants (warfarin, rivaroxaban, etc.) before blood sampling may lead to abnormal coagulation results, which need to be analyzed in conjunction with the medical history. The precautions before blood sampling vary for different blood sampling programs, and patients are advised to prepare for the blood sampling under the guidance of their physicians.