In this paper several kinds of basic common Schroeder diffusers were introduced, and the diffusers were applied on the top of sound barrier. Using boundary element method, the sound barrier structure model was simulated. Significant effects of noise reduction of all diffusers were found in low frequency range with 3～5dB higher than traditional sound barrier. Also it was found that prime root diffuser (PRD) has the better insertion losses up to 0.61~1.52 dB than other diffusers at the 5 m distance back of the sound barriers. The result will provide an important reference to apply sound diffusers on the sound barrier.