Abstract:A new method of transformation between the three dimension geocentric coordinate system and independent coordinate system in adjustment of GPS networks is proposed.Compared with the conventional methods,it is not based on the 54 or 80 national reference ellipsoid.In the present technical situation,it’s easy to get the accurate geocentric coordinates on all control points with GPS.In order to transform the coordinates to the existent independent coordinate system exactly and conveniently,the regional ellipsoid surface approximated to the projection plane is firstly adopted in this mode,and then transformation is realized on Gauss plane.This method not only realizes the accurate transformation between the two coordinate systems,but also provides a complete set of transformation parameters for the whole area for a long period.Analogously it provides also a new simple method which can generate the transformation parameters with 3 known points in the smaller area.