With the development of unmanned aerial vehicle(UAV) technology, UAV scanning technology has been applied widely home and abroad. However, due to its highly-priced, the application of big UAV is not sufficient in the current engineering. The paper introduced the application ways of small UAV in combination with its own experience in the whole life cycle of projects including the earlier-stage of the surveying and design, the application of construction phase, later monitoring and the result of exhibition, and so on. In addition, the paper focused on its practice mode in the fields of water conservancy and hydropower engineering, geological disaster management, and municipal engineering, so as to provide some ideas for the further development of UAV scanning technology, hoping to further promote the application of UAV technology in the engineering full life cycle.