Abstract: Copper thin films with diffrent thickness were prepared by method of physical vapor deposition (PVD), and then the films were annealed in vacuum environment. The X-ray diffraction spectrum were measured by X-ray diffractometer and analyzed by line profile analysis to calculate the crystalline size and microstrain of the prepared copper thin films before and after annealing. The results show that with the increase of the thin film thickness, the crystalline size increased and the microstrain decreased. And after annealing, crystalline size of the thin films obviously grew and the microstrain obviously reduced.