As an important part of the power grid, the frequent dropped calls and other accidents of transmission line seriously affected the safe operation of power systems, and the mostly analyzed reason of accidents is that the quality of pressure fittings of transmission lines do not meet the regulatory requirements. In order to prevent the occurrence of such accidents, it is necessary to study the detection method of crimping quality of the fittings on transmission lines. First of all, this paper presents the use of X-ray detection as a means of non-destructive testing; then, based on the theory of X-ray detection and the actual transmission line detection conditions, the structure of the detection device is designed; finally, the typical crimp quality defects are verified by this device, and various typical crimp quality defects can be displayed clearly, intuitively and visually. This device has realized the quality inspection of the crimping quality of the high-voltage transmission wire fittings, and played an important role in preventing the accidents caused by poor quality of the transmission line crimping.