With the acceleration of infrastructure construction in Shanghai, more and more construction projects need to cross the municipal river channels. In order to ensure the safety of flood control and waterlogging prevention in the region, it is necessary to demonstrate and analyze the impact of river-crossing construction projects. Through the example of the Huinan Bridge crossing the Dazhi River in the Shanghai-Nantong Railway (Phase II) Project, the key points of the river-crossing impact are demonstrated and analyzed from two stages of operation period and the construction period. During the operation period, the site selection and structure of the bridge pile foundation will be reviewed from the perspective of planning compliance, and the stability of the retained and newly built revetments will be reviewed by using the empirical formulas in the specifications. During the construction period, the impact of the construction process on the retained revetment is reviewed through the finite element software such as Midas Civil and Plaxis. And the banked-up water level is reviewed through the practical hydraulics formula. The river-crossing impact is analyzed through the main process and calculation methods, which can provide the reference for analyzing the river-crossing impact in the other construction projects.