Some chemotherapy drugs such as: MTX, 5-FU, 6-MP, Ara-C, 5-DFUR, ADM, EPI, THP, etc. are more prone to mucositis, especially in the use of larger doses can appear serious mucositis or mucosal ulcers, coupled with reduced saliva secretion, gradually lose the role of cleaning and lubrication, oral pH value changes, easy to secondary bacterial and mycobacterial infections. Treatment measures 1, prevention-oriented, in the absence of ulcers, the patient should be routine oral pH test, according to the PH value to choose the appropriate mouthwash for oral care. pH>7.1 prone to bacterial infection, the application of 2% boric acid solution gargle; PH <5.5 prone to fungal infection, the application of 4% sodium bicarbonate or Dobell solution gargle (alkaline); PH in 6.1 -7.1 -7.1, the application of 1:5000 furacilin solution gargle; 3-5 times a day can prevent and reduce the incidence of oral ulcers; 2, strengthen health education. Due to the nausea and vomiting caused by chemotherapy, patients eat less, which affects saliva secretion. Encourage patients to drink more water, rinse more mouth, brush teeth with soft bristles before bedtime and in the morning, which can keep the mouth clean, but also reduce local pain caused by dryness and moisten the mucous membrane, buffer acidic saliva, dissolve sticky saliva and reduce swallowing difficulties; 3. Observe the condition of oral mucosa, whether there is lip and tongue numbness, tongue reduction, bleeding, inflammation and ulcers. When fungal infection occurs, oral mycoplasma should be taken, 4% sodium bicarbonate or 5% hydrogen peroxide to clean the mouth. After the occurrence of oral ulcers, according to the degree of ulcers, clean the shed mucosa, mucus and decaying material to keep the mouth clean and promote mucosal regeneration. Topically, watermelon cream can be applied to the affected area, oral cleansing, Viscum containing or gargling, and esophageal combination containing. Dry mouth and lips can be coated with Vaseline or lip balm; 4, understand the characteristics of ulcers caused by commonly used chemotherapy drugs, targeted oral care, such as MTX and 5-FU are prone to cause oral ulcers, mainly in the lower lip and tongue area, respectively, containing gargle calcium tetrahydrofolate 12mg/500ml, allopurinol 300mg/15ml, can prevent the occurrence of oral ulcers; 5, large ulcers ( 5. Those with large ulcers (oral ulcers and esophageal ulcers) should fast and apply total parenteral nutrition; 6. Observe the change of body temperature to detect infection early and treat it early; 7. Closely observe the change of oral ulcers and pay attention to the skin of the whole body.