Abstract: The inhomogeneous deformation of materials has an important effect on various mechanical properties of mechanical parts. In order to learn the evolution of inhomogeneous strain in ultrafine crystalline copper accurately, the material model was studied for inhomogeneous strain under symmetric cyclic loading. The construction of representative volume units（RVE） from polycrystalline voronoi assemblies and electron backscatter diffraction（EBSD） maps with symmetric cyclic loading; The strain of all element within the RVE was counted and analyzed, and the statistical standard deviation of the longitudinal strain was used to describe the situation of inhomogeneous of deformation. The results show that the strain inhomogeneity of ultrafine crystalline copper during cycling changes with loading and unloading, and the inhomogeneity increases with the number of cycles. The strain inhomogeneity at the peak tensile position is gradually greater than that at the peak compression position.