The precautions after ultrasonic knife include proper rest, dietary regulation, prevention of infection, attention to vaginal fluid, and regular review. 1. Appropriate rest: ultrasonic knife treatment can be applied to cervical erosive changes with contact bleeding and ineffective medication, which needs to be operated by a professional doctor. After treatment, it is necessary to pay attention to appropriate rest, avoiding strenuous exercise and exertion. 2. Regulate diet: Under the guidance of the doctor, increase dietary nutrition, such as increasing protein-rich food, and avoid spicy stimulation and cold food. 3. Prevention of infection: antibiotics such as metronidazole can be given as prescribed by the doctor to prevent infection, and sexual intercourse, vaginal douching and pelvic baths should be prohibited for 4 to 8 weeks. 4. Pay attention to vaginal fluid and bleeding: after the treatment, there will be an increase in vaginal secretion and even a large amount of watery discharge, and there will be a small amount of vaginal bleeding in 1~2 weeks after the operation due to the scab removal from the wound. 5. Regular review: Follow the doctor’s instructions to review the wound healing on time and pay attention to the presence of cervical canal stenosis. If there is any discomfort after ultrasonic scalpel, it is recommended to go to the hospital in time for examination and follow the doctor’s instructions for treatment.