FOD (Foreign Object Debris) refers generally to a certain type of foreign substances that may damage aircrafts or air systems, Currently, FOD monitoring in the vast majority of airports across the world is operated manually. To meet the urgent need for FOD monitoring measures, the imaging technology based on arc synthetic aperture (ArcSAR) is researched, the geometrical model and signal model of ArcSAR are built, and the method described in this paper increases the detection range to the same target by 2~3 times and can effectively inhibit “flickering” clutters such as rain and snow.