Abstract: This paper focuses on the influence of the lining structure on the ray penetration performance in the radiographic testing of composite ceramic thermal insulation structure. The influences of the composite ceramic insulation thickness, the structure of additional plate and the key parameters (tube voltage, exposure time, etc.) of the radiographic testing on the image quality were studied. The results show that the increase of the composite ceramics insulation thickness and the additional plate structure will reduce the contrast sensitivity and image resolution, and hence reduce the image quality; when inspecting welds of composite ceramics and pressure vessels with a fixed thickness, as the tube voltage increases, the image contrast sensitivity decreases. When the tube voltage is 190 kV, the image resolution reaches the optimal value; the increase of the exposure time can improve the contrast sensitivity and the normalized signal-to-noise ratio, so the increase of the exposure time can therefore improve the image quality.