Cube-corner prism is widely applied in laser ranging because of its retro-reflective property. The requirements of its precision are different according to applied cases. The far-field diffractive characteristics of cube-corner prism will directly affect long-distance laser ranging. By the analysis of dihedral angle offset and flatness error of cube-corner, the reflective beam wave aberration distribution of cube-corner is presented and the far-field diffractive patterns are computed. The patterns show that divergence of the emerging beam increases with the dihedral angle offset up to completely separate to six beams; the flatness error will result in deterioration of the patterns and debase the quality of the emerging beam. The diffractive characteristics of cube-corner prism provides an evaluation method and approach to design this kind of prism.