The red light emitted by the red light medical instrument promotes the proliferation of fibroblasts and endothelial cells, increases cell metabolism and promotes cell synthesis, thus accelerating wound healing. Taking the process of wound healing as an example, fibroblasts proliferate through mitosis, synthesize and secrete a large number of collagen fibers and matrix components in 4 ~ 5 days or 6 days, and form granulation tissue with new capillaries to fill the defect of wound tissue and create conditions for the coverage of epidermal cells. After irradiation with red light therapeutic instrument, the wound healing speed can be improved by 2 ~ 3 days.