Abstract: Considering the low intensity of diffraction peak,bad diffraction profile,wide fluctuation range and low accuracy of the stress measurement results for titanium and titanium alloy,the effects of aperture diameter,exposure time,and exposure number on the intensity of X-ray diffraction peak,net intensity, full width at half maximum,and the stress measurement results were investigated through the X-ray stress measurement of free stress standard sample and high stress standard sample. On this basis,the selection method of X-ray diffraction stress measurement parameters for titanium and titanium alloy was decided and used in measuring the residual stresses in TC4 welded joint. Results show that with the increase of aperture diameter and exposure time,the intensity of X-ray diffraction peak increases, both the diffraction profile and the accuracy of the test results are improved. What's more,with the increase of exposure number, the diffraction profile and the accuracy of the test results are also improved. The measurement results of residual stresses in TC4 welded joint meet the requirements of the related standards.