The tidal current fields of the Yangtze estuary with different topography, different projects and different runoff are simulated. The amount of the flood current, ebb current and the net water leak with different tidal stencils and different runoff is counted and analyzed. And the amount of the flood current, ebb current and the net water leak before the implementation of the deepwater channel project and after completion of the deepwater channel phase II project is counted and analyzed.