Baiyangdian wetland is the largest freshwater lake in the North China Plain. It plays a significant role in maintaining the balance of the ecosystem in northern China, regulating regional climate, replenishing underground water sources, regulating and storing flood water, and protecting biodiversity. As an important ecological barrier for the sustainable development of Xiong'an New Area, it is crucial to maintain the stability of water replenishment and improve the hydrodynamic status in Baiyangdian wetland, to ensure the healthy development of this aquatic ecosystem. A MIKE 21 Flow Model was applied to completely understand the influence of multi-water resource replenishment on the hydrodynamic behavior of Baiyangdian wetland. Eight scenarios were considered, including the diversion of the Yellow River into the wetland, middle route of the south-to-north water diversion project, eastern route of the south-to-north water diversion project, and joint replenishment of upstream reservoirs. Subsequently, the following results were obtained: (1) The hydrodynamic behavior at the entrance of Xiaobai river significantly improved under the water replenishment scenarios of the diversion of the Yellow River into the Baiyangdian wetland and eastern route of the south-to-north water diversion project. The improvement area accounted for approximately 15–20% of the total area of the wetland; however, the average velocity of the entire wetland did not markedly improve. (2) The hydrodynamic improvement of the northwest corner was the most noticeable under the water replenishment scenario of the middle route of the south-to-north water diversion project, and the average velocity of the whole wetland increased the most in the case of this scenario. The average velocity of the entire wetland increased from 0.003 m/s to 0.006 m/s, while that of the northwest corner increased from 0.003 m/s to 0.01 m/s after one month of water replenishment. (3) The hydrodynamic circulation of the whole wetland increased the most under the joint water replenishment scenarios of upstream reservoirs due to the dispersion of water entrance. The average velocity of the entire wetland increased from 0.003 m/s to 0.005 m/s after a month of water replenishment. Thus, the results of this study provide scientific support for promoting the circulation of water in Baiyangdian wetland.