Abstract: Described in the paper is the application scope of the overlaying-welding process, covering relevant specific operation steps. In addition, a comparison between the overlaying-welding process and the conventional welding process is made, based on which logic welding sequence and heat treatment measures as necessary are proposed to reduce welding-caused strain and stress. Relevant operation practice shows that the overlaying-welding process is an effective approach to repair of large-sized mechanical component.