There are three methods of hemoglobin collection commonly used in clinical practice, one is venous blood collection, one is peripheral blood collection, and one is arterial blood collection. Venous blood collection is the most widely used type of blood collection, most of the clinical tests require venous blood collection, such as routine blood tests and various biochemical tests, including liver function, kidney function, blood lipids, and most serological tests also require venous blood collection, because of the superficial location of the veins, and at the same time, the changes in the composition of the blood do not have a significant impact, so generally take the venous blood collection method. Peripheral blood collection method because of taking peripheral blood easily in the squeeze when mixed with tissue fluid, venous blood collection method is used less, can be applied to a variety of blood type identification methods. Arterial blood collection method is mainly used in clinical practice to do gas and blood analysis, and by drawing the femoral artery, blood gas analysis can be done.