The resolution of a conventional optical imaging radar system is constrained by the diffraction limit of the telescope’s aperture. The combination of the lidar and synthetic aperture processing techniques can overcome the diffraction limit and provide a higher resolution air borne remote sensor. Atmospheric turbulence is an important factor affecting the lidar imaging, and phase screen simulation method is an effective method to simulate the degradation of laser signal propagating in turbulent atmosphere. This paper proposes a kind of phase screen generation method based on Monte-Carlo random factor. The expansion of phase data units can be selected by Monte-Carlo random factor which can increase the randomness of phase screens. The radar imaging with different turbulence intensity is also calculated in this paper, then the improved rank one phase estimation autofocus method is used to compensate the imaging phase errors. The results show that the method of generating phase screen is consistent with the statistics of atmospheric turbulence, which can well simulate the effect of atmospheric turbulence on synthetic aperture lidar, and the influence on synthetic aperture lidar azimuth resolution is greater when atmospheric turbulence is stronger. Improved rank one phase estimation algorithm has good autofocus effect, which can effectively compensate the phase errors and enhance the image quality degraded by turbulence.