Children with nosebleeds for no reason, may be due to the surrounding environmental factors, may also be sinusitis, leukemia and other diseases related. 1. Environmental factors: dry or dusty environment may lead to nasal mucous membrane dryness and damage, so that the nasal cavity capillary rupture bleeding, so it will cause small children without reason nosebleed. 2. Sinusitis: Sinusitis is mainly caused by viruses, bacteria or fungi caused by sinus infections, usually lead to nasal congestion, pus with blood and other symptoms, which leads to small children nosebleeds for no reason. It is recommended to seek timely medical treatment, medication and surgical treatment under the judgment of the doctor. 3. Leukemia: Leukemia is a malignant neoplastic disease of the hematopoietic system, which usually leads to fever, infection, bleeding and other symptoms, so it may cause small children to have nosebleeds for no reason. Children with nosebleeds for no reason, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, give targeted treatment or treatment.