Acousto-optic modulation of the femtosecond laser beam has wide potential in various fields such as microscopic imaging, micromachining and optical storage because of its rapidity, high accuracy and good repeatability. This paper reviews the latest research on acousto-optic modulation of femtosecond laser, describes the effects of spatial and temporal dispersion of such lasers after acousto-optic modulation, introduces the theoretical outcomes on pulse width evolution of the Gaussian laser pulses after acousto-optic modulation, discusses the characteristics of contemporary dispersion-compensating techniques for the acousto-optic modulation of femtosecond laser, and finally refers to the challenges of this technique.