The water and sediment conditions in the river section of the bridge area are complex，and the choice of bridge pier layout and bridge span affects the evolution of the main navigation channel，navigation conditions，and the total investment in the project. This study employs numerical simulation technology to deeply analyze the water flow conditions in the bridge area before and after the construction of the bridge and determine an economical and reasonable bridge pier layout and bridge span. The analysis comes down to the following two observations：1）The bridge pier layout should suit the changes in the riverbed and the channel as much as possible，thereby preventing the formation of a river section obstructing or restricting navigation. 2）The clear width of the bridge span should meet the requirements of navigation clear width and traffic capacity.