Abstract: A study was conducted on local heating stress relief treatment of thick titanium alloy narrow gap welded joints. The influence of process parameters such as local heating temperature, insulation time, and heating width on residual stress in titanium alloy welded joints was analyzed, and residual stress testing was carried out using drilling strain method. The results show that in the x-direction perpendicular to the weld seam, the residual stress first increased and then decreased with the increase of distance from the center of the weld seam, and a residual stress peak appeared at a distance of 10-20 mm from the center of the weld seam. In the y-direction parallel to the weld seam, the peak residual stress appeared at a distance of 0-5 mm from the center of the weld seam. By increasing the local heating temperature, the residual stress of the welded joint was significantly reduced.