After the sand pillow is thrown from the water surface，it will have a drift distance in the direction of the water flow during the sinking process under the action of gravity and water flow.The sand pillow will still have a certain speed after falling into the river bottom，if the speed is greater than the stopping velocity of the sand pillow，the sand pillow will continue to move，and the movement distance after the sand pillow touching the bed surface is a stable displacement (secondary drift distance).According to the drift rule of sand pillow in dynamic water，combined with the vertical velocity distribution rule，the drift distance calculation formula of sand pillow in the whole process from underwater drift to landing stability is obtained through three drift distance calculation methods，and the comparative analysis is carried out.The results show that when the vertical velocity of the river is exponential velocity distribution，the drift distance formulas derived by using the inertial force method and the comprehensive coefficient method have good applicability.