A 3-year-old child with a nosebleed should take the following measures: 1. When a nosebleed occurs, the child should be kept in a prone position or held face down as much as possible so that the nosebleed will not be sucked back into the trachea and cause asphyxia. 2. Appropriate measures should be taken to stop the bleeding as much as possible. 3. If the nosebleed is serious, it should be sent to the hospital in time for treatment, where the emergency physician or quintuple surgeon can take the necessary measures to stop the bleeding. In addition, relevant examinations should be conducted in the hospital to identify the cause of the disease and then treat it.