A double-side Fresnel lens for a solar energy collector has been designed with the characteristics of lighter weight and smaller axial dimension. Rays going through the front surface ring and entering the corresponding rear surface ring, which reduces the energy loss. The energy of the solar cell obtained by the double-side Fresnel lens is with higher energy density. The design formula for the rear surface Fresnel structure is derived. The optical condenser performance of a double-side Fresnel lens is simulated with an optical design software LightTools. A double-side Fresnel lens with diameter of 200 mm, focal length of 120 mm and F number of 0.6 is designed as an example. The applied illumination is from 380 nm to 760 nm wavelength and with a solar angular subtense of 0.55°. Design results show that theoretical improvement in collection efficiency is 21.1% compared with that of a similar conventional Fresnel lens.