Laser weapons are the important optoelectronic payload for the new generation of combat aircraft concept. In a mobile environment, the far-field focus spot of laser weapons is affected due to external factors such as atmospheric turbulence and vibration impact, which leads to the sharp decrease of energy concentration, and the defocused spot is in urgent need to be repaired in real time. Combined with the optical residual characteristics of low-altitude tactical laser weapons, the system of nonlinear equations between the mirror adjustments of adaptive optics wavefront corrector and the primary aberration Seidel coefficient was constructed, the strong correlative adjustment variables were eliminated by means of correlation coefficient matrix method, and the low-order adaptive optical correction system using a unfocused off-aperture telescope secondary mirror as a wavefront corrector was proposed. The numerical simulation results show that after a finite number of translation adjustments of the secondary mirror, the root-mean-square value of the wavefront error can be quickly reduced to below the diffraction limit, which meets the requirements of laser weapon systems for optical residual correction.