The variations of XRD full width at half maximum (FWHM), residual stress and hardness for the surface of GCr15 steel after triple shot peening (TSP) as a function of annealing time and temperature are studied. The results show that with the increase of annealing temperature and time, hardness and FWHM increase gradually while compressive residual stress (CRS) decreases gradually. CRS and micro-structure work together on the hardness values, and the micro-structure is the most important factor for hardness. According to establishing the quantitive relationship of hardness with FWHM and CRS, the value of hardness can be calculated; a new type of noncontact and nondestructive hardness testing can be realized by XRD method. (C) 2017 Elsevier B.V. All rights reserved.