Mud flat is a special intersection zone between land and sea. It is difficult to get there by human. If we use the traditional mapping mode, it needs to layout a lot of ground control points, which means a great challenge to the mapping. The UAV LiDAR system, integrating high-precision GNSS / INS integrated navigation system, can significantly reduce or even do not need ground control points, to meet the needs of high-accuracy mapping. For areas not convenient to layout control points, the UAV LiDAR is now the most appropriate choice.