Abstract: In view of the complex pressure vessels of thick-walled hydrogenation reactors, the paper introduces the structure characteristics, damage modes, damage position for the thick-walled hydrogenation reactors. The nondestructive testing methods of the main welds, the bead welding, the flange sealed solder and the external structural parts welded with tube for the thick-walled hydrogenation were mainly discussed. The advantages and disadvantages of various nondestructive testing methods were summarized according to the material and structure. The results can provide reference for peers.