Abstract: in this paper,we start from the theoretic accuracy analsis of CCD pushroom scannins mode,use the analogous data,to calculate the influence of satellite based GPS antenna positioning accuracy to the object positioning for ground. Using the same group of test data,the comparisions of ground point determination accuracy among following three cases are down, which includes:1)Only ground control points are used but no GPS observations; 2)Only GPS observations are used but no ground control points; 3)Both ground control points and GPS observations are used. Moreover, the transformation between the geocentrics coodinate system and the tangent plane coordinate system is considered,and also the transformation between the center of GPS antenna and of CCD scanner center. The obtained conclusions are useful for the study of remote sensing information position system for ground and of determing the observation method for satellite based GPS.