Children’s ears are swollen under the root of the ear, may be the insect bite reaction, or mumps, lymphadenitis and other diseases. 1. Insect bite dermatitis: If the child’s ear has recently been bitten by mosquitoes, mites, fleas and other insects, the secretions of the insects will be injected into the skin, which will then cause an allergic skin reaction, and localized redness, swelling, erythema and other symptoms will appear. 2. Mumps: this disease is caused by the mumps virus, the typical symptoms are centered on the earlobe, can be forward, backward, downward development of swelling, can be manifested as swelling under the ear root. 3. Lymphadenitis: The occurrence of this disease is related to germs infection, common in hemolytic streptococcus, staphylococcus aureus, etc. Common triggering factors are cold, upper respiratory tract infections and so on. The main manifestations are swollen lymph nodes, pain, etc. Therefore, the swelling under the ear root of the child may be caused by lymphadenitis. When children are found to be swollen under the root of the ear, they need to go to the hospital in time to clarify the specific cause of the disease.