The left side of the stomach may be caused by intestinal spasm, ureteral stones, skin trauma and other factors. 1. Intestinal spasm: intestinal spasm is common in children, but it can also occur in adults, and it may be related to factors such as unclean diet, cold stimulation and strenuous exercise. When there are the above triggering factors, some patients lie down after overeating and drinking, which will easily lead to part of the intestinal spasm, and the spasm can be alleviated or disappear when walking, so that the left side of the stomach does not hurt when walking and lying down pain phenomenon. 2. Ureteral stones: routinely, if the left side of the ureteral stone patients walking can be no discomfort, but if lying down too fast, may lead to the movement of ureteral stones, which in turn leads to the left side of the waist, abdominal pain and other symptoms. 3. Skin trauma: when there is trauma to the abdomen, because the wound has not healed, normal walking is generally not excessive pulling the skin, when lying down, the abdominal skin is pulled, may cause pain in the wound. The left side of the stomach walking does not hurt lying down pain causes more, it is recommended that the patient timely consult a doctor for relevant examinations to clarify the diagnosis.