Abstract: With the thermal equilibrium equation and double ellipsoidal heat source model on the basis of the principle of energy conservation, the temperature field and residual stress field of the CO₂ gas shielded welded joint components of Q345 corrugated steel web/Q345 flat steel bottom plate were analyzed by ABAQUS finite element software. The variation laws of residual stress in single-sided and double-sided welding were compared, and the influence of the end of the welding path on the residual stress was discussed. The results show that the morphology of the molten pool and the temperature variation curve during welding of the corrugated steel web plate and the flat steel bottom plate obtained by simulation were consistent with the test results in the literature. The maximum relative error of the temperature at the same time was 11.3%, verifying the accuracy of the simulation method. The longitudinal residual stress generated by single-sided welding was greater than the transverse residual stress. The residual stress of the weld toe in the web was relatively low. The residual stress distribution along the weld root and weld toe in the bottom plate was similar, and the overall stress was tensile stress. With increasing distance from the surface of the bottom plate, the transverse residual stress of the bottom plate changed irregularly, while the longitudinal residual stress decreased. Obvious stress sudden changes occurred at the ends of the welding path after single-sided welding. Compared with that after single-sided welding, the temperature peak of the joint component after double-sided welding was higher. The transverse residual stress at weld toe, weld root and in the bottom plate varied irregularly. The secondary heating of the heat source led to a decrease in stress in some areas and the transformation of tensile stress into compressive stress.