Abstract: A new non-destructive method for the determination of metal surface stress in-depth profile has been studied. By selecting a series of different diffraction planes and various X-ray radiations average values of residual stress in different effective penetrating depth of the metal can be obtained. As the X-ray intensity decays with the depth according to exp(-ux), the stress values so determined are weighted average ones, from which the real stress value at different depth of the sample can be calculated, and thus the distribution curve of stress in-depth of the metal part can be drawn.By means of popular X-ray diffractometer the maximun depth measured by this method lies in 40-50u, which depens on the selection of target and the diffraction plane, so the method supported may be available in studying the surface quality of metal parts after surface treatment or grinding. The surface stress values of carbon steel sample, WC cuting tool after grinding and nitrided metal sample have been determined, and the corresponding stress distribution curves obtained.This experiment should be done by a diffractometer with side inclination accessories.