In order to study the joint influence on flood propagation caused by the wharf groups located at different reaches of the Yongjiang River, the influence of the wharf groups on channel flow characteristics under typical tidal and flood conditions was studied based on the numerical model of Delft3D. The results show that the backwater level is higher if the location of the wharf group is farther from the estuary and the distribution of the wharves is denser. In the backwater influencing region induced by different single wharf groups, the increase of flood level caused by all of the wharf groups is higher than that caused by each wharf group. In the area where both backwater and water level drop caused by different wharf groups exist, part of the water level variation can be balanced out. However, due to the degree of water level drop is lower than the backwater, water level during flood discharge still increases. The velocity decreasing zone surrounding the wharf project and the velocity increasing zone in the main channel both show a zonal distribution. The velocity variation caused by all of wharf groups is more than that induced by every single wharf group and the degree of velocity reduction is greater than velocity increase.