The diagnostic criteria for hypoproteinemia are generally a total protein of less than 60 g/L or an albumin of less than 35 g/L. There are many causes of hypoproteinemia, including various reasons for the decline in total protein and albumin, which includes not only albumin but also globulin and fibrin. The main components are still albumin and globulin, and the role of albumin and globulin on the human body is more obvious. The causes of the decline of albumin include insufficient intake, malnutrition, excessive excretion, excessive consumption, and insufficient synthesis, and the decline of albumin will thus cause the decline of total protein. Too little albumin synthesis is seen in liver cirrhosis, too little intake is seen in malnutrition, inadequate intake, intestinal absorption disorders, too much excretion is seen in nephritis, too much consumption is seen in chronic diseases, febrile diseases, burns, malignant neoplastic diseases. In addition, if there is a significant decrease in globulin, it may also cause a decrease in total protein, which can be caused by congenital or acquired immunodeficiency, taking immunosuppressive drugs, etc. Therefore, for hypoalbuminemia or hypoproteinemia, patients should pay attention to identify the cause and give treatment according to the cause.