Role and mechanism: ◆Stress effect: Shock wave can pass through body fluids and tissues to reach the affected area, when it enters the human body, due to the different media it contacts, such as fat, ligaments, tendons and other soft tissues and skeletal tissues, different mechanical stresses will be generated at the interface of different sound-resistant tissues, which is manifested as different tensile and compressive stresses on the tissues. Tensile stress can induce inter-tissue relaxation and promote microcirculation; compressive stress can induce elastic deformation of cells and increase cellular oxygen uptake, so as to achieve the therapeutic purpose. ◆Cavitation effect: The negative wave pressure at the end of shock wave pulse can cause cavitation reaction. When the pressure on the hydrodynamic field is lower than the saturation air pressure of the liquid, the molecules in the liquid will enter into the cavitation reaction nucleus and make it expand into the size that can be observed, which is the cavitation effect. Cavitation effect is the unique characteristic of shock wave, which is beneficial to dredge the occluded microvessels and loosen the adhesion of joint soft tissues. ◆Analgesic effect: local high-intensity shock wave can produce super-stimulation to the nerve endings, blocking the transmission of painful signals to the cerebral cortex; the shock wave can cause the change of free radicals around the cells and release the pain-suppressing substances, so as to achieve the therapeutic purpose of analgesia. ◆Metabolic activation effect: Shock wave can accelerate the metabolism of tissues, reduce the reaction of the affected area and accelerate the healing of tissues by promoting the growth of the relevant production factors and the expression of stem cells, promoting the local blood circulation and changing the permeability of the local cell membrane of the tissues.