Abstract:A new method which is called Height Substitution Circular Method is put forward aimed at the solution of the sevenparameter transformation between 3D and 2D spaces with unknown height. The feasibility and the applicability of this method are proved through processing the real data and the simulated data. The results show that when both the ranges of longitude and latitude are less than 8°,both the coordinate differences in \%x\% and \%y\% direction are about 1 cm and the accuracy is obviously improved with the range reduction of longitude and latitude especially the range reduction of latitude.