Induction straightening is an effective method for welding deformation correction of thin plates due to its high efficiency and controllability, while causing the redistribution of welding residual stress, leading to a reduction in manufacturing precision. In order to study the influence rules of induction straightening process on post-weld surface longitudinal residual stress redistribution, the straightening process of T-joint welds is used as an example, and the distribution regularities of surface longitudinal residual stress under different straightening process are experimentally obtained. The internal mechanism of residual stress distribution under different straightening modes including straightening above the back of the weld and straightening on both flanks of the back of the weld are studied through the combination of finite element simulation and a three-bar analytical model. Two combined induction straightening modes of different sequences are designed, whose influences on residual stress redistribution are theoretically predicted and experimentally verified. The results show that the combined mode of straightening above the weld first and straightening on both flanks of the weld later is an effective method for reducing surface longitudinal residual stress at the welding seam. The research results can provide a certain reference for the rational design of induction straightening process so as to control post-weld surface longitudinal residual stress.