Abstract: The antenna pattern of ground-based radars deployed at a specific location will split in the vertical direction due to the multipath effect. Multipath propagation significantly affects the detection performance of ground-based radar in low frequency. In this paper, the theory of multipath propagation effect is discussed, and the effect on radar detection range and accuracy is analyzed quantitatively. On this basis, reflection position adjusting and frequency diversity are designed to eliminate the multipath effect and even promote the detection range. The proposed design offers a certain significance for the site optimization of ground-based radar and detection performance improvement.