Abstract: By element unactive technology and ellipsoidal heat souce, temperature field of T joint in subsection welding was analyzed and then the influence of welding sequence on welding residual stress of T joint was studied by numerical simulation. The results show that the subsection welding not only increases the low residual stress region of the whole welding seam, but also effectively decrease the stress peak of some region in welding seam with reasonable welding sequence and welding direction. For the priorwelding subsection, the shorter distance to the latter welding subsection, the better effect for decreasing welding residual stress. Moreover, the effect of the latter welding subsection' s quenching arc region on decreasing residual stress of the prior welding subsection is better than the striking arc region.