The causes of the left abdominal pain under the ribs and old fart are functional dyspepsia, irritable bowel syndrome, gastritis and gastric ulcer. 1. Functional dyspepsia: mainly caused by gastroduodenal dysfunction, mainly manifested in the left abdominal subcostal pain, distension, burning sensation, dyspepsia, the gastrointestinal tract bacteria fully fermentation of food, which will lead to an increase in the production of gas, manifested in the farting and so on. 2. Irritable Bowel Syndrome (IBS): pain in the lower left side of the abdomen, relieved by defecation or elimination of gas, increased gas production and palpable salami-like intestinal tubes. 3. Gastritis: especially chronic gastritis, which can be manifested as vague pain in the left abdomen under the ribs, diarrhea, nausea, vomiting, etc., with hyperactive bowel sounds and increased gas production. 4. Gastric ulcer: patients with gastric ulcer are often infected with Helicobacter pylori, which can lead to accumulation of gas in the gastrointestinal tract, accompanied by left abdominal subcostal pain, heartburn. Therefore, the left abdominal subcostal pain has more causes, the patient should be timely consultation, early diagnosis, timely treatment, so as not to delay the condition.