The invention belongs to the technical field of cable inspection and maintenance management, and particularly relates to an endoscopic cable rust detection method and device. The detection method includes the steps of obtaining images of surface appearances and rust states of steel wires in cables to be detected through a miniature endoscopic imaging device, obtaining gray-scale statistical characteristics of the images through image processing, recognizing relevant quantitative characteristic information, judging rust development tendency according to image matching in same position at different times and recognition algorithm, and judging the surface rust states and rust degrees of the steel wires in the cables to be detected through digital image correlation analysis and fuzzy mathematics membership function according to the gray-scale statistical characteristics and the quantitative characteristic information, obtained through laboratory tests, of the steel wire surface images under the conditions of different surface appearances and different rust degrees. The detection method has the advantages of being large in detection region, high in detection efficiency, high in reliability, strong in applicability and simple in installation; the detection device has a small size, the practical application is convenient, and the cost is low.