Clinical manifestations of small intestinal digestive enzyme deficiencies include bloating, belching, abdominal pain, diarrhea, and possibly malnutrition over a long period of time. The small intestine is an important place for digestion and absorption of food. The small intestine contains digestive enzymes such as enteropeptidase, pancreatic amylase, trypsin, lipase, and digestive juices such as bile and gastric acid, and the food stays in the small intestine for a long time, so that it can be fully digested, decomposed and nutrients absorbed. Insufficient digestive enzymes are often caused by inflammation of the digestive tract, tumors and other diseases. Therefore, when the small intestine does not have enough digestive enzymes, the food stays in the digestive tract for a long time, which may show symptoms of indigestion such as bloating, belching, acid reflux, etc.; also due to stagnation of food, the gastrointestinal peristaltic movement is weakened, which leads to abdominal pain; the indigestion of fat and other foods leads to diarrhea; and the prolonged nutritional maldigestion and malabsorption leads to hypo-proteinemia, vitamin deficiency and even affects the growth and development. Therefore, if symptoms such as indigestion occur, it is recommended that the cause of the disease be clarified in time and actively treated.