Abstract: In order to address the issue of decreased circularity in the diffracted beam due to a mismatch in momentum at the acousto-optic modulator caused by the differing dispersion angles of the acoustic and optical wave vectors, the intensity angular spectral analysis and transmission matrix analysis methods were adopted, and the technical solution of pre-compensation using a cylindrical lens in front of the acousto-optic modulator was proposed. Theoretical analyses and experimental verifications were carried out. The results show that the circularity of the corrected diffracted beam remains almost unchanged throughout the transmission path at 0.98 to 0.99, which is close to the initial ellipticity of 0.985. This is achieved while maintaining approximately 90% of the system’s diffraction efficiency. The results demonstrate that the degradation of diffracted luminous circularity resulting from momentum mismatch in acousto-optic modulation can be effectively addressed. Furthermore, the acousto-optic modulator's modulation rate, diffracted light circularity and the overall energy utilization of the system can be balanced. This study provides a reference solution for realizing high-quality beam diffraction in high-speed acousto-optic modulation.