This paper put emphasis on the elements of influence elevation metric precision in aerial photogrammetry, The elevation metric precision is low in the UAV low-altitude photogrammetry. We design wide-angle and light small dual combination of low-altitude aerial camera system can solve the problem. Moreover, This paper illustrate its composition, dual combination of wide angle digital camera principles, and the use of the system for large scale mapping of the production process, Theory and Practice shows that, use the way of width mosaic has an advantage in the aspect of improve elevation metric precision.