The volume holographic storage optical system can be simplified, using the common optical axis for signal beam and reference beam by locating two diffusers on both sides of the incident plane. However, in this kind of holographic storage optical system, the total numerical aperture for signal beam and reference beam is much larger than the numerical aperture for signal beam. The design requirement and optical parameter determination about signal optical path and reference optical path in this volume holographic storage optical system have be analyzed. In order to correct aberration in positive optical path and reverse optical path for the object beam, and meet the demand of reference beam at the same time, the multi-configuration method has been adopted to optimize the positine and reverse optical path of the object beam and the optical path of the reference beam. A holographic storage optical system with common optical axis for signal beam and reference beam achieving diffractive-limit has been designed. The focal lengths of the front and rear group lens are 33 mm and 30 mm, respectively, its front work distance is 30 mm, its back group lens has 30 mm focal length, its total numerical aperture for signal beam and reference beam is 0.53, and the wave aberration of the system is less than 0.071λ.