A principle scheme of optical synthetic aperture imaging ladar (SAIL) processor is proposed, the temporal-spatial conversion, imaging resolution and the processing capability of this processor are analyzed by the virtue of data collection equation of side-looking/down-looking SAIL, verified experiment is performed, and the imaging results of the collected data of our SAIL demonstrator are displayed. The optical SAIL processor is compact, lightweight and has the ability to real-timely and on-site process the SAIL data, which has a promising application prospect in onboard and satellite borne SAIL systems.