In order to solve the problem of the roundabout crossing illumination, a design method of lens with circular spots is proposed based on the theory of etendue conservation in non-imaging optics. Through the designed single lens and lens arrays, the circular spot can be obtained by simulation of TracePro software. The simulation of single lens shows that the illumination uniformity of the target surface is reduced with light source size increasing, but the efficiency keeps unchanged. The illumination uniformity of the target surface is about 86.5% and the efficiency is about 90.3% when the size of light emitting diode（LED） source is 5 mm×5 mm. For the three kinds of lens arrays, the illumination uniformities are more than 91% and efficiencies are more than 90% by setting the appropriate initial parameters. This design is in comformity with the design standards of road illumination.