The wire harness is an electromechanical optical device installed in front of the output window of the X-ray tube assembly sleeve. Its main function is to control the irradiation field of the X-ray tube output line, so as to minimize X-ray imaging and diagnosis. The projection range can avoid unnecessary doses, and can absorb some scattered rays to improve the impact of clarity. In addition, it can also indicate the projection center and the size of the projection field. Wire harness is an indispensable auxiliary equipment for X-ray projection and protection.