Four-year-old children with sudden nosebleeds need to be compressed first to stop bleeding, and then need to clarify the cause of the sudden nosebleeds may be related to environmental dryness, nose picking and other physiological factors, but also may be related to nasal septum deviation, aplastic anemia, etc., such as recurrent bleeding needs to be clarified as soon as possible to the hospital cause, and to take surgical, medication and other treatments. 1. Physiological factors: dry environment can cause nasal mucosa dry bleeding, through the sea salt water nasal spray and other methods can be relieved. If the nose picking damage mucous membrane caused by bleeding, can first be pressed to stop bleeding, if necessary, can be used under the guidance of a doctor ephedrine nasal drops to shrink the nasal mucous membrane blood vessels, reduce bleeding. You should change the habit of picking your nose. 2. Deviated nasal septum: It means that the nasal septum partially protrudes, or deviates to one side or both sides, which causes nasal congestion, headache, nosebleed and other nasal dysfunction symptoms. When the symptoms are obvious, mometasone furoate nasal spray can be used for symptomatic treatment. If the deviation is obvious and affects the ventilation, surgery is needed if necessary, such as septal submucosal resection and septal submucosal correction. 3. Aplastic anemia: it can be manifested as anemia symptoms such as pallor and fatigue, which can be accompanied by bleeding gums and nosebleeds, etc. It can be firstly pressed to stop bleeding, and then follow up with component blood transfusion to control the bleeding tendency, and cyclosporine can also be used for immune-suppressing treatment. The occurrence of four-year-old children suddenly nosebleed, parents can first pressure to stop bleeding, such as bleeding or repeated bleeding, should promptly seek medical attention, under the guidance of the doctor to identify the cause of the treatment.