Since there is no atmosphere in space, problems such as atmospheric turbulence and atmospheric attenuation do not exist. Therefore, spaceborne Synthetic Aperture Lidar (SAL) has a better application prospect than ground-based and airborne SAL. In order to verify the feasibility of airborne SAL imaging, a spaceborne SAL imaging model was established, and the coherent accumulation time and PRF were derived. Then, a satellite orbit model was established by using the extrapolation method of the two-body motion. Next, according to the limitation of the radar antenna beam width, the antenna pattern of the lidar was calculated, and a method to obtain the maximum synthetic aperture time was proposed by using the target gain curve's 3 dB beam width. Finally, six kinds of spaceborne SAL imaging modes were established through simulation, and the imaging parameters under different modes were analyzed, which verified the feasibility of spaceborne SAL imaging. The research of this paper lays a foundation for the research of spaceborne SAL imaging algorithm.