In recent years, the Unmanned Aerial Vehicles (UAVs) have aroused increasing interests among experts for such civilian applications as disaster monitoring, surveillance and spatial decision-making support. The high-resolution orthoimage generated from the UAVs video image stream can be used as a basic map for planners and decision-makers to make decisions by obtaining high precision geospatial data through registering, compiling, measuring and analyzing the orthoimage. This paper presents the methods for producing the true orthoimage from UAVs streams. The IOPs are calculated by using iteration algorithm having the EOPs obtained from GPS and INS system as initial values, and these parameters are used for rectification of UAVs image. Experimental results show that all the orthoimages are of high accuracy under the condition that DEM/DSM,DOQQ and UAVs video image have the same resolution.