The additional hydrodynamic load produced in the process of navigation chamber going into & out of navigation pool is the main problem on development of chamber-launching ship lift.The VOF model,the κ-εturbulence model,and the dynamic mesh method are used to build a 3D mathematical model for simulating the hydrodynamic characteristics of the water-entry process of navigation chamber.The result shows that the 3D mathematical model built in this paper is more accuracy and stability,which can simulate the complex flow patterns in navigation pool produced by the navigation chamber entering into water.By the 3D mathematical model,we analyze the fluctuation and flow distribution characteristics have been analyzed when the navigation chamber enter into water with different velocities to the third stage vertical ship lift of Goupitan hydropower station.The calculation results are in accordance with the experiment results.