In order to obtain the detailed information on mechanism of the motion of a single droplet formation process in the pulsed sieve-plate column, the numerical analysis for transient behavior is carried out by using VOF (volume of fluid) method, and their results are compared with the experimental results. On the assumption that the essential shape of the pressure pulse added to the system can be described numerically by a simple sine wave, the numerical results agree approximately with the real drop Formation process. The mechanism of the fluid flow inside and outside a drop can be clear from the obtained numerical results, and it is found that there is a circulation flow inside a drop. Furthermore, it is confirmed that VOF technique is useful and efficient as the method for tracking boundary interfaces and can predict numerically well the transient behavior of the drop with liquid-liquid interfaces.