Abstract: Aiming at the application background of airborne radar low-altitude target detection， this paper establishes a modified multipath detection model for FDA （Frequency diverse array） radar target detection at low-altitude incident angles. Besides， a multipath interference suppression method based on FDA radar is proposed. And the generalized likelihood ratio test （GLRT） method with no training data realizes the detection of moving targets in a multipath propagation environment. The simulation results show that the range-angle dependence caused by the FDA radar frequency offset can effectively suppress the multipath reflected echoes at low incident angles， and thus can significantly improve the detection performance of low-altitude targets.