There are many reasons for the swelling and pain of half of the gums at night, such as apical periodontitis, pulpitis, periodontal abscess, etc. It is necessary to choose the appropriate treatment according to the different reasons, such as local rinsing and medication, surgical treatment, periodontal therapy, etc. 1. Periodontitis: Inflammation that occurs in the apical tissues of the tooth, manifested by spontaneous pain and swelling of the gums, the pain of biting will be aggravated at night, causing half of the gums to swell and hurt. Need to carry out root canal treatment, at the same time can follow the doctor’s instructions to take drugs such as metronidazole, ibuprofen, etc. for anti-inflammatory and analgesic treatment. 2. Pulpitis: manifested as spontaneous pain at night, the pain can not be localized, the pain tends to attack at night, more intense than during the day. Patients can be treated with surgical treatments such as root canal therapy, pulpotomy, apical induction molding and so on. 3. Periodontal abscess: Inadequate oral hygiene can cause bacterial growth and destruction of periodontal tissues, causing gum swelling and pain. Local rinsing and medication are needed, and pus formation needs to be incised and drained, and periodontal system treatment is carried out at a later stage. If the symptoms of half of the gums at night have not been relieved, there may be other reasons, we should go to the hospital in a timely manner, active diagnosis and treatment, so as not to delay the condition.