Because many recent epidemiological studies have reported the associations of population’s proximity to high traffic roadways with adverse health effects, interest in how roadside structures affect the concentration of motor vehicle emitted pollutants in the near-road microenvironment has increased. These noise barriers may affect pollutant (for example: odor, carbon dioxide, particle et al.) concentrations around structure by blocking initial dispersion. This study examined the effects of roadside barriers on the flow patterns and dispersion of pollutants from high traffic highway. The effects of noise barriers were examined using commercial software FLUENT. The results show noise barriers increase concentration of near noise barrier wake region and decrease concentration in the faraway distance from noise barrier. The results also show far from emission position (between 100 m and 200 m) surface concentration of multi-barrier cases are 2 times lower than that of no barrier case.