Abstract: In order to reduce the speckle interference in the multimode fiber emission fields, we investigated whether the coupling of different diffraction grades derived from Bragg acoustooptic diffractive effect to multimode fiber could reduce the speckle field contrast. Through the analysis on the speckle field contrast subsequent to the changing of the sound field frequency, we demonstrated that the anisotropic crystal TeO2 could regulate the contrast of speckle field and improve Gaussian distribution. It is probable that Bragg diffractive effect could reduce the speckle field interference.