The stools of 3-month-old breastfed babies are normally unformed and soft, mostly yellow or yellowish-green in color, may have a small amount of mucus, and there is no separation of water and stool. In the clinic, stool examination is an important project, according to the shape and color of the stool, to detect some diseases, usually 3 months breastfeeding baby’s stool is normal for the unshaped soft paste stool, mostly yellow or yellow-green, there may be a small amount of mucus, there is no pus, with blood, water and stool separation phenomenon. However, if the stool is eggdrop soup-like, it suggests that there may be rotavirus infection or norovirus infection; black stool suggests that there may be gastrointestinal bleeding; rice slop-like stool suggests that there may be Vibrio cholerae infection, etc. In addition, the stool may be shaped like a soft paste, with a small amount of mucus. In addition, the frequency and volume of stools can also be used to reflect the body’s intake. Parents should pay attention to the shape and color of the baby’s stools in the course of raising the baby, etc. In case of abnormality, they should observe the baby’s performance carefully and seek medical consultation at the hospital if necessary.