A 3-year-old’s nosebleed can be caused by various factors, including deviated nasal septum, dry nasal congestion, atrophic rhinitis, nasal foreign bodies, and may also be related to blood diseases such as abnormal platelet count or quality, and abnormal coagulation mechanism. Further examination is needed to determine the cause, and treatment should be under the guidance of a doctor. In daily life, drinking plenty of water and paying attention to diet can help the child recover quickly.