Abstract: This paper describes the existing cases of specimen reconstitution, and summarizes the process and characteristics of arc stud welding, electron-beam welding, laser welding and surface active joint. A comparative analysis of the advantages and disadvantages of these welding methods has been carried out, and the quality monitoring method in the process of reconstitution and after reconstitution is listed. The application of reconstitution technique in nuclear engineering is analyzed, the gap between our existing experiences and international advanced level is analyzed and the direction of improvement is pointed out. It is proved that arc stud welding and electron-beam welding are the most widely used techniques, and the laser welding is available for any type of specimen.