We investigate the dynamic evolution of wave packet under the coupled diabatic potentials via employing the time-dependent wave packet approach. The wave packet splits in the crossing region due to the influence of non-adiabatic effects. In our studies, it is found that the non-adiabatic effects are very important to the dissociation of NaI molecule, and it becomes markedly with the increase of evolutionary time. Moreover, our study shows that the mean packet position 〈R(t)〉 and the classical trajectory R(t) are nearly coincident and the dissociation probability is dependent on the laser wavelength.