Radar imaging geometry, which performs imaging in the direction of slanting range at the sample time of electromagnetic echo reflection, is quite different from optical imagery. The hypsography results in not only the layover distortion of groundtruth under different imaging conditions, but also the inconsistency of intensity distribution of imaging gray. Consequently the positioning performance of radar scene matching is directly reduced. A real time adjustement method based on vertical projection, by means of analyzing the relationship between the ground elevation and the model of radar imaging, is proposed to adjust the geometric distortion of sidelooking real aperture radar image. Experimental results show that the method is effective.