Abstract: Deformation monitoring is an important support for the safe operation of dams.Aiming at the problem that SAR satellite cannot use traditional digital terrain to obtain the elevation phase of dam side in arch dam deformation monitoring, this paper proposed a new arch dam deformation monitoring method by high-resolution SAR satellite combined with3D point cloud.In this method, the distance-Doppler model was used to transform the3D point cloud of a dam towards the radar direction, and the interference baseline information was used to accurately simulate the dam heights.Finally, the dam horizontal deformation projection to sight direction was carried out to realize the deformation field extraction of the arch dam with millimeter accuracy.The engineering application showed that the observed horizontal deformation accuracy of the dam body can reach about4mm.With the improvement of the resolution and the increase of the number of SAR satellites, this method is expected to achieve higher frequency and higher precision dam deformation monitoring.