Medical fiber endoscopes have been applied in various medical fields, and the overall light effect level of fiber endoscopes can affect the quality of the received images, leading to medical staff being unable to accurately judge the condition of the lesion. To quickly and effectively evaluate the comprehensive mirror body light effect of fiber endoscopes in clinical use, an automatic detection method based on image processing was proposed. The high reflectivity standard whiteboard was illuminated by the endoscope light source, and the endoscope images collected by the CCD camera were processed. The ratio of the gray values at 90% of the field of view to the center of the field of view was extracted as the comprehensive body light effect of each edge point, and the overall comprehensive body light effect of the endoscope was further calculated. According to the design method, 10 sets of repeated experiments were conducted on 2 fiber endoscopes, and compared with trademark values of the manufacturer. At the same time, the uncertainty was calculated and the source of error was analyzed, verifying the feasibility of the designed method.