The invention provides an intracavitary visible photodynamic therapeutic instrument. The instrument comprises an endoscope or inner endoscope, a laser light source and a laser conductive fiber, wherein one end of the laser conductive fiber is arranged in a cold light source channel of the endoscope, while the other end is connected with the laser light source; the endoscope or inner endoscope is one of a laparoscope, a joint endoscope, a thoracoscope or neuroendoscope, a gastroscope, a cystoscope and the like. The instrument realizes visible lighting in a body cavity by using the endoscope or inner endoscope, and introduces the laser light source to the lesion location in the body cavity so as to provide clear view for implementing gross resection surgeries, radiate by laser, and increase time for killing tumor cells. Furthermore, the instrument has small toxic or side effect, overcomes the defects of local cancer tissue invasion, lymph node metastasis, hematogenous metastasis, tumor cell detachment and implantation and the like which cannot be solved by chemotherapy, radiotherapy and other means. Based on application of photosensitizer, the actual range of a malignant lesions can be displayed, and 'target lesion' can be treated actively. The instrument has reasonable and simple structure, and can provide visible lighting in the body cavity to implement effective treatment on the 'target lesion'.