Recently, the crystalline plasticity based finite element technology has revealed the great progress in the field of mesomaterial mechanics to study the strength and formability of sheet metal. For this phenomenological mesomaterial modeling, the parameter identification is required by employing the experimental results of single and polycrystal material deformations. In this paper, a hardening-softening evolution equation is newly proposed and embedded in the elastic/crystalline viscoplastic constitutive equation. The uni-axial tension tests of pure aluminum single crystal under the condition of different directions between the crystal orientation [010] and the tensile axis, have provided the stress-strain relationships, slip lines and strain localization patterns. It is demonstrated that numerical results of deformation and strain localization of single crystal sheet tension show good agreements with the experimental observations, which elucidate the anisotropic effect on the deformation clearly.