Abstract: Lightning causes the burst of shock wave because cf instantaneous release of energy in the canal. In this paper, the motion of lightning shock wave and its effect on motion of cloud droplets are calculated. The equations of motion of cloud droplets under action of lightning shock wave are discussed. The motions of cloud droplets under the action of lightning shock wave are calculated for some cases. The calculation shows that lightning shock wave strikes the droplets strongly and forces them to move a distance. The droplets with different sizes gain different velocity of motion. The influence of lightning sHock wave on the coalescence growth of droplets is also discussed.