Malabsorption syndrome is a syndrome caused by various causes of malabsorption of nutrients from the small intestine, which must undergo adequate digestion. The clinical manifestations of malabsorption syndrome, in addition to the characteristic symptoms and signs of the primary disease causing malabsorption, are mainly a series of pathophysiological changes caused by a variety of nutrient absorption disorders. Clinical diagnosis is as follows: 1, diarrhea and abdominal pain: diarrhea in most patients can be frequent or intermittent episodes, due to impaired fat absorption, can lead to steatorrhea, the typical person’s stool is light-colored, large, greasy or foamy, often floating on the surface, and most have a foul odor. The diarrhea of patients with impaired absorption of fatty acids and bile salts can appear as thin stools. However, 5% to 20% of cases can be clinically free of diarrhea and even show symptoms of constipation. Abdominal pain is mostly distension, rarely colic, often before defecation, and may be accompanied by mild pressure pain and flatulence. 2, wasting, weakness, easy fatigue: this is due to fat, protein and carbohydrate absorption disorders resulting in reduced absorption of calories, but dehydration, low potassium, loss of appetite is also an important factor. Severe patients can present cachexia, weight loss of 10-20kg or more. 3, vitamin and mineral absorption disorders: iron absorption disorders can lead to iron deficiency anemia. Vitamin B12 and folic acid absorption disorder can lead to megaloblastic anemia. Calcium, magnesium, potassium, vitamin D absorption disorders can cause abnormal sensation, hand and foot convulsions, vitamin K absorption disorders can make patients have a tendency to bleeding, petechiae, black stool and hematuria. Vitamin B deficiency can cause tongue inflammation, stomatitis, stomatitis, foot disease, etc. 4, edema, ascites, nocturia, fever: mainly manifested as hypoproteinemia, peripheral edema and ascites may appear, water absorption disorder nocturia, due to malabsorption, immune function is reduced, so it is easy to infection, there may be fever manifestation. 5, cow’s milk intolerance: due to impaired absorption of lactose, manifested as colic, gas and diarrhea. The level of mucosal glucokinase can be decreased in such patients, and the Flat lactose tolerance test is positive.