Abstract: In 3D positioning of cranio-maxillary bone based on X-films,we add two oblique position scout views on the base of A-P（anterior-posterior） and side position ones.as a result,we obtain 4 scout views of cranio-maxillary bone in its X-films with regard to 0°,45°,90° and 135° positions respectively.By this improvement we reconstruct the characteristic points of the cranio-maxillary bone,and at the same time correct the errors.