Abstract: The internal structure analysis of the magnetic coil was using industrial CT to avoid the difficulty of disassemble magnetic coil during failure analysis. The computed tomography (CT) imaging characteristics for internal defects of resin matrix composite products were studied and analyzed. The results show that industrial CT is able to effectively detect various defects of the fault magnetic coil such defects as breakage of enameled wire, inadequate installation of components, fusing of enameled wire, winding deformation, porosity in the envelope, excess wire or metal impurities, et al. industrial CT can accurately determine t the location and geometry of the defects. The analysis of Industrial CT application has guidance significance for improving the quality of magnetic coil and production technology.