Abstract: With the significant increase in the demand for urban bridge construction, the efficient assembly welding construction of steel box girders has become one of the hot issues of great concern. Based on the secondary development of ABAQUS software in Python language, a double ellipsoid heat source model was adopted on the basis of thermal-structural coupling analysis function. Considering convection and radiation, the welding temperature, stress and deformation fields of single plate rib were obtained under different welding sequences. Comparative analyses of the deformation under different welding spacings and welding sequences were carried out for multi-piece ribs. The results show that for a single plate rib, changing the welding sequence and spacing has a greater impact on the welding stress and deformation field. Compared to non-simultaneous welding, the residual stress of the two corner welds of a single plate rib welded at the same time is smaller in the transverse path and larger in the longitudinal path. However, the residual deformation generated by simultaneous welding is generally smaller than that generated by non-simultaneous welding, reducing by about 10%. For multiple plate ribs, when the welding spacing is 600 mm, the residual angular deformation curves of the plate ribs under different welding sequences almost overlap. And when multiple fillet welds are welded simultaneously, the overall residual deformation generated is relatively small, reducing by about 10%. The research results can improve the efficiency of steel box girder assembly construction to a certain extent, providing reference and inspiration for the construction of similar bridges.