There are many causes of gum swelling and pain in 3-year-old babies, which may be caused by normal physiological factors, such as teething, or by disease factors, such as dental calculus, herpetic gingivostomatitis, gingivitis, periapical inflammation, etc., and need to be dealt with accordingly according to the causes of gum swelling and pain. 1, teething: when babies are teething, their teeth will drill the top of their gums, and they will have symptoms of gum swelling and pain. At this time, parents can massage the gums with clean, slightly cool gauze or cold compress the gums with ice wrapped gauze to relieve the symptoms of swollen and painful baby gums; 2, dental calculus: babies with dental calculus will lead to swollen and painful baby gums. Tartar will make the baby’s teeth surface attached to yellow-white or brown-black tartar, and accompanied by bleeding gums and oral odor symptoms. When the above symptoms are found, parents should promptly take the baby to the dental hospital for treatment, usually with ultrasonic scaling to treat; 3, herpes gingivostomatitis: herpes gingivostomatitis is a disease caused by viral infection, the baby’s gums can appear swollen, pain, ulcers, etc.. At this time, you need to seek medical attention, under the guidance of a dentist for anti-inflammatory treatment to relieve the symptoms of swelling and pain, and do a good job of home isolation; 4, gingivitis: a common symptom of gingivitis in babies is gum swelling and pain, you can use a soft-bristled toothbrush or cotton balls with saline or warm water to wipe the baby’s gums and teeth, and under the guidance of a doctor to use topical drugs such as iodine glycerin to relieve the baby’s gum swelling and pain. After the symptoms of baby gum swelling and pain are completely relieved, you can let the doctor scrape the plaque and hard tartar on baby teeth to avoid the symptoms of baby gum swelling and pain again; 5, periapical inflammation: baby caries affects the dental pulp or trauma causes inflammation of dental pulp, which may cause pulpitis and then develop into periapical inflammation, which often results in tooth pain, gum swelling and pain and other symptoms. Gum swelling and pain can be relieved by medication, while root canal treatment or extraction of the affected tooth after pulp drainage is performed. When a baby has swollen and painful gums, parents should not give the baby antibiotics or analgesics without permission, but should promptly take the baby to the hospital for appropriate treatment under the guidance of the doctor to relieve the symptoms of swollen and painful gums.