Itegrated high-power LED light source have been applied in many practical lighting engineering, but the illumination of the integrated light source is not very satisfactory. In order to solve the problem that integrated high-power LED light source cannot be applied directly in the field of illumination, a downlight reflector and a lens was designed by using the source-target map based on the energy conservation law in non-imaging optics. These two types of optical devices were simulated in Tracepro software, which obtained a good uniform round lighting spot. The simulation results show that the illumination uniformity is reduced with light emitting area increase. The illumination uniformity of the round lighting surface is above 95% when the source size is 1 mm×1 mm. The illumination uniformity is decreased to 85% when the source size is increased to 10 mm×10 mm. This research is conformed with the higher uniformity standards of indoor lighting design.