The numerical simulation method of thermal blooming adaptive optics (AO) phase compensation is studied. Collimated beam instantaneous thermal blooming phase compensation is simulated by using the laser atmospheric propagation four-dimension (4-D) code which is independently developed. The effect of deformable mirror (DM) actuators layout on the phase compensation efficiency under different thermal blooming strength is numerically analyzed. The results show that the layout of DM actuators has great effect on the AO system close-loop control stability. When the layout of DM actuators is different, the variance of DM actuators commands is also different. The proper layout of DM actuator can improve the AO system close-loop control stability, increase the threshold value of phase compensation instability (PCI).