The invention discloses a distortion correction algorithm for an optical system of an all-view 3D measuring instrument. The algorithm comprises the steps as follows: 1, establishment of a distortion relation: constructing a mapping relation between coordinates of a standard image and coordinates of a distortion image and generating a distortion correction coefficient file or a distortion correction form file; 2, correction of the distortion image: correcting the input distortion image by using the generated distortion correction coefficient file or a distortion correction form file to obtain a corrected standard image finally. With the adoption of the algorithm, stereo measurement errors caused by image distortion because of optical lens manufacturing and adjustment errors can be effectively reduced, the angle measuring accuracy of the system is greatly improved, and the problem that measurement errors are produced due to the fact that lens distortion reduces geometric position accuracy of objects in images is solved.