Ultraviolet light acts on the human body, light energy causes a series of chemical reactions, anti-inflammatory, analgesic, anti-rickets effect, commonly used to treat purulent inflammation of the skin and other dermatitis, pain syndrome, rickets or chondromalacia, etc.; infrared light mainly in the form of thermal radiation acts on the human body, the local circulation is improved after heat, edema absorption, pain relief, tissue repair, clinically used to treat soft tissue injury, strain, arthritis, etc. Visible light, red light for central nervous excitation; blue light, green light for sedation; blue-violet light for neonatal bilirubin encephalopathy has curative effect. Although the laser has the commonality of light, but has its own characteristics, can be used for physical therapy, can also be used in surgery.