Abstract: Matching welding materials, postwelding heat-treatment and reasonable welding procedure of 0Cr16Ni5Mo martensitic stainless steel are introduced in this paper. M831A electrodes, double U groove and symmetric welding by both side are determined through tests. With postwelding heat-treatment of 950℃/2h oil quenching and 500℃/10h tempering, the welded joints obtain desired performances.