With the development of computer technology, especially the emergence of high resolution image sensor, aerial photogrammetry has played an important role in geological survey. Traditional aerial measurements are carried out by manned large aircraft, with a large volume of measured information and a wide range of shots. This method is suitable for large area operation, which is high and expensive for hardware site. UAV air measurement systems are usually used for small area measurements. The UAV is small and fluctuates greatly during flight, the collection of the data and images are not accurate enough. This paper has obtained the accurate measurement of image by studying the image fast matching theory, which has practical significance in the actual mapping and has higher research value.