The bloating and pain in the upper abdomen after sitting down may be caused by eating too much, gastritis, colitis and other reasons. 1. Eating too much: when patients eat too much, indigestion, will cause the abdomen and stomach is too full, thus appearing after sitting down on the abdominal distension phenomenon. 2. Gastritis: due to irregular diet, Helicobacter pylori infection, etc. will make the patient appear gastritis, gastritis patients will appear after sitting down the phenomenon of epigastric distension. 3. Colitis: due to the influence of factors such as poor immune system and heredity, it will cause patients to have colitis, and patients with colitis will have epigastric distension and pain after sitting down. When the patient appears to sit down after the phenomenon of epigastric distension, it is recommended to consult a doctor in a timely manner, diagnosed by a professional doctor, and given reasonable treatment.