One year old baby a nostril nosebleed may be nasal foreign body, nasal swelling, rhinitis and other related, should be timely consultation to identify the cause. 1. Nasal foreign body: children naughty to the nose stuffing things lead to nasal foreign body, resulting in mucous membrane damage, there may be a nostril nosebleed situation. 2. Nasal swelling: due to nasal growths, such as benign or malignant tumors, when the tumor breaks down, the symptom of nosebleed may occur in one nostril. 3. Rhinitis: the nasal mucosa is congested and edematous, the brittleness is increased, and one year old babies with one nostril nosebleed may appear. A one-year-old baby with a nosebleed may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.