Abstract: According to the selection rule of road section where sound barriers will be built and a lot of factors being fully considered, such as the traffic noise, the pollution degree, the population being polluted, the features of the road and spot condition, those road sections were selected exactly by using step-by-step sieve method. The investigation shows that the height 12～15 meters of buildings closing the road is the most seriously polluted by traffic noise, the main frequency of which is 500～2000 Hz and frequency distribution basically has nothing to do with the style of the road and vehicle.