In the process of UAV image used as an analysis object to measure the river surface velocity, the shaking of UAV will cause the shaking of the shooting picture, resulting in comparatively great errors in the measurement results. In view of this flaw, based on the flight information recorded by UAV, two UAV image correction methods, with and without the reference point, are developed respectively, thus realizing the orthophoto correction of UAV image conveniently and quickly, followed by an effective solution of problem of the negative influence of UAV shaking on the velocity measurement results. Combined with the optimized image velocity measurement and analysis method, the field velocity measurement is carried out in experimental river as well as natural river, thus obtaining more accurate measurement results of river surface velocity.