Five-month-old baby poop with sour smell, may be physiological, may also be pathological; physiological reasons need to adjust the lifestyle, pathologically caused by the need for targeted treatment under the guidance of the doctor, such as medication, general treatment and so on. 1. Physiological: If the baby is breast-fed, there is a possibility of lactose intolerance and milk protein allergy, resulting in sour stools, which should be adjusted according to the child’s feeding situation. Giving lactose-free milk powder or amino acid milk powder may provide relief. Lactase can also be taken orally for treatment. 2. Pathologic: (1) Indigestion caused by eating too much for a short period of time, irregular feeding, etc., can also occur as mentioned above. Oral medication such as Bacillus subtilis bacillus granules can be given to regulate the intestinal flora, and oral digestive medication such as compound pepsin powder can be given to help relieve the symptoms. Abdominal massage can also be performed to help relieve the symptoms. (2) Intestinal bacterial, viral and other pathogenic infections can lead to enteritis, there is a sour odor of the stool this situation, such as bacterial infection, according to the allergy oral antibacterial drugs such as cefixime; such as viral infections, with self-limiting, can not be special treatment. At the same time can be taken orally such as bacillus subtilis bacillus granules to assist in the treatment. Five-month-old baby stool has a sour odor, parents should take the child to the doctor in a timely manner, diagnosed by the doctor to give targeted treatment, do not blindly self-medication. The above drugs should be used in accordance with medical advice.