Airborne lidar surveying and mapping technology has the advantages of vegetation penetration，strong flexibility，high precision，and safe operation. Unmanned aerial vehicle（UAV）needs no special take-off and landing field and features flexible operation，convenient transfer，and low cost. The combination of such technologies can quickly obtain the surface 3D point cloud data，which is widely used in many fields. In Phase II of the Heishazhou waterway regulation project，the UAV airborne lidar surveying and mapping technology is conducted multiple times in key local areas in different stages to obtain high-precision surface information. Combined with the underwater topographic data obtained from multibeam bathymetric surveying，the data of filling，siltation，collapse and scour are comprehensively analyzed and evaluated before，during，and after regulation. It guides the engineering design，construction，monitoring，and acceptance，which provides a technical example for similar engineering practices.