Bacteria are the most important factor in the development of periodontitis, so the key to treating periodontitis is to control them. Generally speaking, periodontitis treatment is divided into four stages: 1. The basic treatment stage aims to remove or control clinical inflammation and bite pathogenic factors by selecting conventional treatment methods for periodontal disease, including teaching patients how to maintain oral hygiene, extracting teeth with poor prognosis and unfavorable restoration, supragingival scaling, subgingival scraping to remove plaque and tartar, selecting antibacterial drugs to control inflammation, and bite jaw adjustment. Through thorough local treatment, the process of periodontal tissue destruction can be stopped and the lesion can be induced to turn into a stationary phase. 2, periodontal surgery treatment and fixed of loose teeth. 3.Permanent restorative treatment, usually performed 2-3 months after surgery. 4.Review and retreatment phase, once every six months, including checking plaque control, hygiene promotion and radiographic examination for further development of treatment plan. The key to the success of periodontitis treatment is two things: 1, thorough treatment plan and meticulous and superb treatment by the doctor. 2, patient adherence to good self plaque control. The latter is more important than the former, otherwise the doctor’s work will be half-hearted, and the disease will occur again. In general, if patients can adhere to good self-plaque control, most of them have obvious efficacy on treatment. However, there are a few patients (about 10%) who do not do well with any treatment and continue to get worse rapidly until they lose their teeth, which is called “refractory periodontitis”. The treatment of periodontitis in diabetic patients requires special attention. The incidence of periodontitis is high among diabetic patients. This is because diabetic patients have low resistance to infection and high blood glucose, which can lead to plaque formation and periodontitis. Periodontitis, in turn, further increases the chances of infection in diabetic patients. Therefore, diabetes and periodontitis can be said to be a vicious circle that promotes each other. Diabetic patients should pay more attention to the treatment of periodontal disease. Firstly, they should control their blood sugar level, secondly, they should systematically treat periodontitis, and usually they should pay more attention to oral health care and regular review.