Ultrasonic knife, also known as high-intensity focused ultrasound therapy, how often it is done is related to the patient’s treatment purpose and cannot be generalized. Ultrasonic knife can use ultrasonic positioning to penetrate the human body after focusing ultrasonic waves and form high temperature above 60℃ in the tumor area to destroy tumor tissues without damaging the surrounding normal tissues. When used for tumor treatment, it can be done 1-2 times a year according to the patient’s specific condition. When used for cosmetic treatment, ultrasonic knife can penetrate energy to the dermis and fascia layer without damaging the epidermis, stimulating collagen reorganization and regeneration in the muscle to achieve skin tightening, wrinkle removal, shaping and other cosmetic effects. The effect can generally be maintained for 2-3 years. The specific time is closely related to the power of the ultrasonic knife, the power is large may be relatively long duration, low power may be shorter duration, patients can wait until the effect is not obvious according to the specific situation. Although ultrasonic knife has more advantages, but patients may also have certain indications and adverse reactions, need to combine their own situation, consult a professional doctor.