Dynamic formation and detachment of drop from a capillary tube at low flow rate was investigated by the method of numerical simulation.The full transient process of the formation and detachment of drop was simulated numerically by solving the NavierStokes equations using an algorithm based on the finite volume method.The tracking of the free surface was achieved using the volume of fluid (VOF）technique and the geometric reconstruction was based on the technique of piecewiselinear interface construction (PLIC).Dimensionless elongation length and dimensionless minimum radius against relative time scale was analyzed in the present work and there is a good agreement between the numerical simulation results and experimental results.Not only the development of shape and axial velocity

but also the relationship between the formation and annihilation of the vortex rings in the droplet was investigated.The relation of the pressure on the axial line and the position of the neck and pinchoff of the droplet was investigated by studying the variance of pressure on the axial line.