The properties of plastic lens applied in 3D virtual displays are studied and a Polymethyl Methacrylate (PMMA) optical system for glasses-type virtual displays is presented. By using a reflector, the beam path of the system is folded, which leads to a compact structure. A binary optical element is introduced into the system to effectively correct the chromatic aberration and wavefront aberration. The imaging quality is improved, at the same time, system size and weight is greatly reduced. The total weigh of the optical system is just 9.8 g, the astigmatic and lateral color which need to be correct in visual system are 0.31 mm and 8.8 μm respectively, and the distortion is less than 7%. The full field of view is 32° and the angu1ar reso1ution is 0.8 mrad.