Abstract: This paper presents the studies of the datum transformation of Ikonos-2 imagery based on RPC model, the mode of the control point distribution and the method of Ikonos stereo triangulation, so that Ikonos imagery can be used to collect the precise geospatial data and produce the large scale map. The Ikonos geopositioning result shows that the accuracy is under 0.95m and 0.55m for plane and height respectively in high mountain area with several ground control points in 600 square km.