According to the evaluation indexes of road lighting, the light distribution of Light Emitting Diode(LED) luminaries was optimized. A mathematical model of the illumination distribution for LED luminaries was established based on the relationship between the evaluation of road lighting and the illumination distribution. By taking the evaluation indexes of road lighting as the optimization conditions and the ratio(Q) of average luminance to average illuminance of road surface as an optimization target,the light distribution was obtained by solving a constrained optimization problem. Finally, the optimized light distribution was induced into lighting simulation software to simulate the LED luminaries for an asphalt trunk road. The result shows that the light distribution is asymmetric in the lateral direction, and the maximum intensity direction leans to the traffic lane. The light distribution saves 30.3% in energy consumption compared to traditional symmetrical light distribution. Moreover, the Q value is 0.072 7, which is higher than that of the normal asphalt trunk road. The evaluation of the road lighting meets the standard of CJJ 45-2006, and demonstrates that the lighting parameters are optimized well.