The design,manufacture and inspection of the surface are difficulty in manufacturing industry,and it influences the development of tobacco machines.The inspection of profile of the tobacco machine parts is one of the high technology.The inspecting technique of data files is suggested in the reversing engineering of the machine parts in the paper.The principle and application will be expounded with the disk-shaped cam and cylindrical cam;it is compared with the profile data files of the products in the reversing engineering,the relative evaluation of the profile deviation of cams can be rapidly accomplished,and it can be used in the quality test and control in reversing engineering.The principle can be applied to the precession research in metrology engineering and mechanic manufacture.