In order to optimize the technology of overlay weld repair of structure of nuclear-grade weldolet weld. Based on the Abaqus software,the 3 D finite element model is established,combined with double ellipsoid source model and birthdeath element,the simulation calculation analysis of the overlay weld repair is carried out,the distribution of temperature field and welding deformation and also residual stress on the process of overlay weld repair is analyzed. Based on the calculation results,the analysis of the influencing factors of surfacing welding is carried out. The results show that compressive stress is formed on the inner side of the original weld structure;from the inner side of the weld structure to the surface of the surfacing layer,the compressive stress gradually transforms into tensile stress;and the residual stress decreases continuously as the increase of the welding speed,also the welding deformation and residual stress can be effectively reduced by using the alternating anticlockwise-clockwise welding sequence. The results of this research can provide reference for the optimization of overlay weld process.