A 5 mega-pixel lens system is designed with ZEMAX. The mobile lens is composed of 3 plastic aspheric lenses. The F-number is 2.8 and FOV is 64°.The sensor OV5645 has 5 mega-pixel which is made by Omnivision, whose pixel size is 1.4 μm×1.4 μm, so the limiting resolution is 358 lp/mm. The final design result shows the optical total length is 4.163 mm, the MTF value is more than 0.3 in full fields of view at 1/2 limiting resolution, the relative illumination is more than 55%, the distortion is less than 1%, and the field curvature is less than 0.1 mm. It possesses an excellent imaging performance.