Over the lasts two decades equal channel angular pressing (ECAP) has been widely used to produce ultrafine grained microstructures with excellent mechanical properties in metallic materials. In this paper, a crystal plasticity finite element method (CPFEM) investigation has been carried out to examine the texture evolution and deformation heterogeneity of copper single crystals deformed by ECAP process. Two single crystals were simulated to examine the influence of initial crystallographic orientation. In the first crystal, the 111â€ slip plane and the 1̄10 slip direction have been rotated by 20° in a clockwise direction around the transverse direction from the theoretical shear plane and theoretical shear direction of the ECAP die, respectively. By contrast in the second crystal, the 111â€ slip plane and the 1̄10 slip direction were rotated 20° in a counter-clockwise direction. The results of the simulation show that the initial crystallographic orientation has a great influence on the deformed geometry, formation of the corner gap, distribution of the plastic strain rate and texture evolution when copper single crystals are undergoing ECAP process. The crystallographic rotation patterns during deformation have been quantitatively estimated and the predicted textures are consistent with the experimental results in the literature. The deformation behavior and orientation development of two copper single crystals with symmetrical orientation to the ideal shear plane during ECAP process have been successfully studied by crystal plasticity finite element method model. The significantly influence on the corner gap formation and morphology of plastic deformation zone has been observed. Simulation results agree well with the earlier published experimental measurements.