Abstract: Axial and tangential surface residual stresses of 304 stainless steel thin-wall welded pipe were measured by X-ray stress tester through different methods. The surface residual stress change of the alloy before and after heat treated at 950 ℃ for 30 min and water cooling was studied. The results show that the data was stable and absolute error was small by the method of Cr Kβ and radiation  2 mm collimator. There was large residual tensile stress on the surface of the 304 stainless steel thin-wall welded pipe before heat treatment. And the tangential residual stress was greater than the axial residual stress. The surface residual tensile stress changed to compressive stress after heat treatment.