The PDT device uses photochemical reactions of photosensitive substances to produce reactive oxygen species, which can damage tumor cells and cause tumor cells to degeneration and necrosis, while normal cells can absorb the laser, this is called photodynamic therapy. Normal cells metabolize faster than tumor tissues, so normal cells are almost unaffected and can be selectively treated for cancer with small side effects after operation.The PDT device limits the absorption wavelength of the photosensitive substance to 620-670nm. The YAG-OPO laser has the wavelength variability corresponding to the absorption wavelength of the new photosensitive material.