Abstract: The post weld heat treatment process of the weld between the first ring and the second ring in the containment was simulated by SYSWELD software, and then the residual stress and deformation of the whole circle and segment of the containment was calculated and analyzed. Afterwards, the effectiveness of the simulation was proved by comparison with experimental residual stress results, and the rationality of the partial segmentation heat treatment method was determined by combining with the actual situation of the project. Therefore, the research provided an effective way for post weld heat treatment of the nuclear steel containment with large wall thickness and large volume.