The concentrator in solar concentrated photovoltaic system was studied. The advantages of Fresnel lens for solar concentrator and its focusing characteristics and optical efficiency were analyzed, and the designing formula of point focus Fresnel lens with flat surface outward and Fresnel surface facing to the solar cell was obtained. Based on the theory of non-imaging optics, the ray trace simulation was realized in the non sequence model of ZEMAX software, and the solar energy distribution on focal plane of Fresnel lens for a certain size was analyzed and simulated. The simulation results show that, the solar energy of focused facula generated by usual Fresnel lens mainly focuses on the centre of the solar cell, and as the distance from the centre increases, the energy density of the concentric rings decreases. To make the solar energy distribution of the solar cell even, the second concentrator in concentrated Photovoltaic should be added.