The utility model relates to an optical path device in an image data collecting device. The optical path device in the image data collecting device includes an image capturing device, at least a pair of movable reflector, a light guide reflector, a parallel telescopic structure and a to-be-tested piece, wherein the movable reflector is composed of an upper reflector arranged in an angle of 45 degrees taking the horizontal line as a reference and a lower reflector arranged reversely in an angle of 45 degrees. The upper reflector and the lower reflector are perpendicular to each other. The movable reflector is fixed on a moving end of the parallel telescopic mechanism. The image capturing device is fixed on a fixed end of the parallel telescopic mechanism. A light collecting lens fixed in the image capturing device is corresponding to the upper reflector in the movable reflector through an optical path. The light guide reflector is arranged right above the to-be-tested piece fixedly. The light guide reflector is arranged fixedly for making the light guide reflector corresponding to the to-be-tested piece and the lower reflector in the movable reflector respectively through optical paths. By adopting the above structure, the optical path device in the image data collecting device provided by the utility model has characteristics of changing directions and shortening length of a device greatly.