Based on the SYSWELD software, a 3D finite element simulation is performed to investigate the temperature field and residual stress in the repair weld process of P92 steel plates. The results show that large tensile residual stresses are generated in the repair weld and the heat-affected zone (HAZ), which gradually decrease with distance in the surrounding base metal. With an increase of the repair length, the transverse residual stress decreases in the middle of plate surface, the HAZ and the weld metal. The longitudinal stress shows a declining trend in the weld metal with an increase of the repair length, while in the middle of plate surface and the HAZ, the longitudinal stress is only minimally affected by the repair length.