The construction of a hydroelectric project will impact the interaction between surface water and groundwater downstream, potentially disrupting the ecological balance of the downstream wetland water bodies. This study focuses on the effects of the Dongzhuang Reservoir construction on the downstream Jingwei Wetland and conducts numerical modeling calculations of unstable three-dimensional groundwater flow under various operating conditions. It simulates and predicts the variations in water level burial depth at different sections of the wetland protection area and at different distances from the riverbank. The study determines the area of water level changes with and without hydraulic engineering under various conditions, and analyzes the impact of groundwater level changes on vegetation area under different adverse scenarios. The research reveals that the construction of the Dongzhuang Reservoir will have a certain impact on groundwater levels in the Jingwei Wetland. Under the most unfavorable conditions of five consecutive years of drought, the maximum water level drop can reach up to 0.54 m. The range of groundwater burial depth variations under different conditions is between 0.249 km2 to 0.432 km2, with the impact on the vegetation area of the protection area relatively small (all less than 2%). The most extreme adverse effects only occur in individual months, and overall, the operation of the project has a minimal impact on the protection area. This study provides important theoretical support for the harmonious and healthy development of the Dongzhuang hydropower project and the ecological balance of the Jingwei Wetland.