Surface deformation of a large-aperture mirror is affected by the mechanical stress produced on its support points in the process of system adjustment. Moreover, in the process of testing, a change in temperature will also lead to a change in surface deformation. Correct determination of the direction and magnitude of the stress plays a decisive role in solving the wavefront change caused by the stress change in a large-aperture optical system. A new approach for correctly determining the direction and magnitude of the stress, which combines a simulated annealing algorithm and integrated analysis technology to establish the linear relationship between the surface deformation of the mirror and the stress on its support points, is proposed in this paper. Through the simulation, accurate recognition of stress location, direction, and magnitude can be realized, with a stress magnitude recognition accuracy of more than 75%.