There are many reasons for stomach pain in the second half of the night, which may be caused by physiological reasons, such as eating too much or eating indigestible food at night. It may also be caused by pathologic factors, such as peptic ulcer, acute gastritis, gastroesophageal reflux disease, etc. It is recommended that the patient seek medical examination as soon as possible. 1. Physiological reasons: eating a lot of food at night or eating too greasy or hard and indigestible food, leading to indigestion, thus inducing stomach pain in the second half of the night. 2. Pathologic causes: (1) peptic ulcer: if you often have stomach pain in the second half of the night, and the pain is prolonged and recurrent, it may be a gastric ulcer or duodenal ulcer causing focal pain. (2) Acute gastritis: if eating cold, spicy and stimulating food or unclean diet at night can lead to acute gastritis, resulting in stomach pain in the second half of the night. (3) Gastroesophageal Reflux Disease (GERD): manifested by the upward surge of stomach acid as well as burning pain, accompanied by the symptom of bitter taste in the mouth, this condition may be GERD, which causes stomach pain in the second half of the night due to gastric reflux. There are many other reasons for stomach pain in the second half of the night, if the patient often occurs in the second half of the night stomach pain, should go to the hospital in time to identify the cause of active treatment.