Abstract: The diffraction peak of Al(111) plane in an aluminum sample was measured repeatedly for 8 times at a fixed point by using an XL-1 type short wavelength stress analyzer, and then peak locations, integral intensity and full width of half maximum intensity(FWHM) were determined by using cross correlation method and parabola method, and relative deviations of repeated measurement for 8 times were calculated. The stress statistical errors for aluminum plate were also evaluated according to sin2ψ stress measuring technique. The results show the relative deviations of measuring repeatability for Al(111) plane peak locations determined by cross correlation method and parabola method were 0.144‰ and 1.27‰, and that of measuring repeatability for integral intensity and FWHM were 5.38% and 5.56%, respectively. The stress statistical errors were 7.56 MPa and 6.64 MPa from cross correlation method and parabola method, and the errors in the error range permitted by a conventional X-ray stress measurement.