The principle of ultrasound physiotherapy instrument is to use ultrasound to penetrate into the deep soft tissues, promote local soft tissue blood circulation, accelerate the absorption of inflammation so as to achieve the therapeutic effect. It has the following hazards: 1, if the ultrasonic treatment time is too long or heat control is not standardized, it will lead to the skin or deep soft tissue burns, scalds, if the deep soft tissue burns, may lead to deep soft tissue inflammation or even muscle necrosis. 2, may lead to the formation of subcutaneous hematomas, such as poorer coagulation function or long oral Anticoagulant drugs in the population, easy to appear subcutaneous capillary bleeding and lead to the formation of subcutaneous hematoma. 3, if for the acute inflammation and edema do ultrasound physiotherapy, may lead to inflammation and edema is more powerful, may also cause systemic infection.