The greenish color on the back of the buttocks of infants can be considered to be caused by skin trauma, pigmented nevus, etc., and can be judged according to the specific manifestations. 1. Skin trauma: when the skin is hit by foreign objects, green patches will appear easily, and the baby’s buttocks may appear green patches after being hit by foreign objects. 2. Pigmented nevus: pigmented nevus occurs on the back, buttocks and waist, but it will not affect the baby’s health and can be treated by laser elimination. There may be other reasons for the greenish color of the back of the baby’s buttocks, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment under the guidance of the doctor.