Airborne laser is influenced by atmospheric optical effect obviously. Thus it is useful to study the beam shaping system represented by adaptive optics, which would effectively improve the beam quality of laser at the target position. It is a feasible solution to use an adaptive mirror in the optical path by energy feedback, to calibrate the laser beam quality emitted by the airborne laser unit. An optimization algorithm, represented by the Stochastic Parallel Gradient Descent method, SPGD method, was applied in the adaptive mirror. It realized the maximum energy of return light, so as to improve the beam quality on the target. By optimizing SPGD algorithm and simulating a global convergence, a practical method of rapid convergence was proposed for beam quality correction of continuous laser and reproducible pulse laser. The simulation of the above algorithm is helpful to improve the performance of laser under an airborne condition, which would have a certain practical value.