Abstract: In order to study the residual stress distribution law of the large diameter arch rib girth weld joint, this paper uses ANSYS software to carry out the numerical simulation of the welding temperature field and stress field of the arch rib girth weld with a diameter of 1 400 mm and a thickness of 26 mm. The thermal cycle curve of the characteristic node is obtained,The contour of temperature and the stress distribution as well as the residual stress distribution and formation process are analyzed. The results show that the peak value of the equivalent tensile residual stress appears at the bottom of the weld on the inner surface of the steel pipe. the radial and circumferential residual stresses form compressive stress in most areas of the inner and outer surfaces in the end. The axial residual stress forms a tension-compression stress distribution and The equivalent residual stresses are tensile stress on both surfaces. During the formation of residual stress,the residual stress curves including the radial,the circumferential,the axial and tht equivalent of the 2nd to 7th layers are almost unchanged coMpared with the first layer, except for small changes in the wave trough and peak.