Sudden nosebleeds in children may be caused by nose picking, dry nasal mucosa, nasal hemangioma and so on. 1. Nose picking: If children pick their nose, it will easily lead to rupture of nasal mucous membrane, which will cause sudden nosebleed, but most of them will bleed from one side of the nostril. 2. Nasal mucosa dryness: mostly seen in the north of the fall and winter seasons, due to the less moisture in the air, it is easy to lead to nasal mucosa dryness, the brittleness of the capillaries increases, and it is easy to rupture and bleed. 3. Nasal hemangioma: if a child has a hemangioma in the nasal cavity, when the hemangioma ruptures, it will often cause a lot of bleeding. Sudden nosebleed of small children may also be caused by other reasons, it is recommended to go to the hospital in time to find out the cause of the targeted treatment or treatment.