A theoretical study of the aberration decoupling and the algorithm of aberration limited for a double mirrors adaptive optical system including a large scale stroke deformable mirror and a high spatial frequency deformable mirror is presented. By adding a limitative aberration vector in the gradient response matrix of high spatial deformable mirror, the voltage of actuators of two deformable mirrors is calculated, and the two deformable mirrors can correct the low-order aberration and high-order aberration respectively. The situation that double deformable mirrors in an adaptive optical system correct the low-order aberration and high-order aberration respectively has been simulated. The result indicates that the close-loop correction performance of double deformable mirrors adaptive system is almost the same as that of the adaptive optical system with an ideal stroke deformable mirror.