In the 4D numerical simulation of laser atmosphere propagation, for considering the effect of laser beams jittering, the relation was discussed between jittering angle of laser and low order coefficient Zernike polynomial. A simulation method of laser beams jittering was given. For proving the correctness of the method, the beam expansion angular radius was calculated with atmosphere turbulence and jittering effect. It is basal consistent with the result of numerical simulation and theory, the all validate that the method is effective.