An optical system for a laser riflescope includes, an objective lens group (1), an eyepiece lens element (3) defining an optical axis with the objective lens group, and an erector lens group (2) positioned between the objective lens group and the eyepiece lens element. The eyepiece lens element includes an aspheric element having a diffractive configuration (33). The aspheric element combines with a spherical lens so as to form a hybrid lens. Thus, the spherical aberration of the optical system is eliminated by the aspheric element and the chromatic aberration is eliminated by the diffractive configuration.