Green stools in 3-month-old babies may be related to the mother’s or baby’s diet, or due to baby’s lactose intolerance or infection, and it is recommended to consult a medical professional for treatment. Common causes I. Dietary factors 1, mother’s diet: during breastfeeding, taking iron supplements, eating a lot of acidic foods or foods rich in iron, such as pig’s blood, will lead to the baby’s stools appear green; 2, baby’s diet: milk powder contains more mineral components, the baby can not be fully absorbed, resulting in stools become green, generally no need to deal with. Second, physiological and pathological factors 1, lactose intolerance: baby lactose intolerance, breastfeeding and lactose-containing food feeding will lead to green stools, dilute, or even watery stools; 2, infection: a few babies due to staphylococcus aureus infection caused by enterocolitis, which can lead to green stools. Treatment is generally symptomatic treatment, such as bacterial enteritis, can follow the doctor’s instructions to use cephalosporin or penicillin treatment, or take lactobacillus tablets, pepsin to regulate intestinal flora. Precautions usually pay attention to the baby’s diet, avoid eating or breastfeeding too much, pay attention to the hygiene of the diet, it is recommended that mothers eat more vegetables, fruits, prohibit cold, spicy, stimulating food. Usually pay attention to keep warm, prevent the baby from being cold, you can gently rub the baby’s abdomen to promote gastrointestinal digestion.