Serum albumin, also known as serum protein, is the most important component of human plasma protein, serum albumin role mainly has two aspects, one is to maintain the body’s normal nutritional status: long-term malnutrition, serum albumin concentration will be significantly reduced. When the nutritional status improves, serum albumin concentration will rise, the second is to maintain the plasma and other colloid osmotic pressure, blood because plasma albumin molecular weight is small, but the density is high, can be adsorbed in the water in the blood vessels, if the serum albumin concentration decreases, water will be permeated from the blood vessels to the outside of the blood vessels, there will be a situation of tissue edema.