Abstract: In order to study the impact of the on riverine flood, a two-dimensional hydrodynamic numerical model in northern riverine Ecological Park Project in Qingyuan District of Ji'an City of Jiangxi Province area was established based on MIKE21 software. The model uses the Finite volume method to discretize the calculation area, simulate the impact of the project's flood discharge water level and flow field, and compare and analyze with theoretical formulas. The results show that the variation amplitude of flow velocity at various frequencies before and after the construction of the project is relatively small, and the typical section flow velocity with the greatest impact after construction is reduced by 1.66% compared to before construction; The overall water level of each design flood frequency shows a decreasing trend, with a maximum decrease of 0.164 m (flood frequency P=1%), only showing an increase in water level near some buildings; This project basically does not affect the implementation and operation of flood, drainage, and water-intake projects planned for the upstream and downstream river sections. It has little impact on existing water projects and other engineering facilities, and has little impact on the water rights and interests of other third parties. The research results can provide technical support for flood impact assessment for the development of ecological park construction projects, and can provide reference for flood assessment of similar projects.