Assuming the requirements of optical design and the precision of the optical manufacturing are satisfied, the key of high imaging quality in an optical system is to assure the accuracy of alignment after assembling all the mechanical components. In accordance with a three-mirror off-axis aspherical system, a new way is put forward. Autocollimating interferometric measurement at multi-field of view is used to get a set of aberrations representing the system misalignments. The aberrations are regarded as the revised target. A least-square computer optimization algorithm is used to predict mirror adjustments. Once the misalignment is determined, it is proved the feasibility of correction theoretically. The theoretical and the numerical analysis are given. The results demonstrate the possibility and effectiveness of this computer-aided alignment method.