For correcting the phase aberration in wavefront, a wavefront sensor-less adaptive optical (AO) system was set up, and a real number encoding Gauss mutation genetic algorithm which was applied to control a 61-channel deformable mirror (DM) was developed. Phase aberration generated by randomly adding voltages to the 61 channels of DM was brought to an ideal incident wavefront. Several simulation experiments have been done. The simulation results demonstrated that this algorithm could find the optimum DM shape which was applied to correct phase aberration. After the phase aberration in incident wavefront was corrected with this technique, the peak light intensity on the focal plane could at most be improved by a factor of 30, and the encircled energy Strehl ratio was increased to 0.96 from 0.032. It is also found that the convergence and stability of the 61 voltages on the DM is quite well.