The invention discloses a small-scale surveying and mapping method based on an unmanned aerial vehicle and a CORS technology. According to the method, the small unmanned aerial vehicle with a high-definition camera is used and combined with the CORS measuring technology to quickly establish a three-dimensional image model for a target, then a geological phenomena and a geological object in the three-dimensional image model are effectively recognized, a boundary is marked, boundary control points are imported into an electronic map to draw the geological phenomenon and the boundary form of thegeological object, and finally small-scale surveying and mapping are completed. Compared with a traditional small-scale engineering geological surveying and mapping method, the efficiency is remarkably improved, and the problems that view fields of surveying and mapping staff are limited, functions of optical measuring instruments are insufficient and surveying and mapping result precision errorsare large are effectively avoided; large-area engineering geological surveying and mapping tasks can be efficiently and accurately completed.