Stomach pain and left back pain are related to gastric ulcer, gallbladder disease and pancreatic disease. Gastric ulcer is a common digestive disease, mainly caused by the damage of the protective barrier of the gastric mucosa and the emergence of ulcer surfaces, especially when gastric acid touches the ulcer surfaces, it will cause severe stomach pain, and some people’s gastric ulcer occurs in the area of the greater curvature of the stomach, and when spasmodic pain occurs, it will cause a certain degree of involvement on the left side of the back, and causing pain in the left back. The gallbladder is below the stomach, so gallbladder disease will cause the involvement of the stomach, inducing pain in the stomach. The pain of the gallbladder is radioactive, mainly radiating to the right back, and there will also be symptoms such as high fever, nausea and vomiting in the body. When pancreatic diseases appear in the area of the tail of the pancreas, since the tail of the pancreas is on the left side of the body, the pain will also radiate to the stomach and the left back, and some people will also experience pain in the left back shoulder.