When laser beam propagates through the strong turbulent atmosphere, phase vortex existing in the distorted wavefront makes the correction of adaptive optics system decline. By establishing a near ground laser propagation model, the distribution characteristics of phase vortex under different scintillation levels and the correction of adaptive optics system were analyzed. In order to investigate the reason why the phase vortex cannot be effectively corrected, the correction result of deformable mirrors with different number of actuators is analyzed when the wavefront distortion is completely restored. Results show that the adaptive optics system using the direct slope method can only correct the continuous phase, but not the discontinuous phase composed of phase vortices. And after the wavefront distortion with phase vortices is effectively restored, the continuous surface deformable mirror can correct the discontinuous phase. At this stage, the key factor limiting the correction effect of the adaptive optics is whether the wavefront distortion can be effectively restored.