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.