Taking a river-crossing tunnel in Shanghai as an example, the factors of fully using the underground space, playing the function of road traffic and protecting the surrounding environment are comprehensively considered. The open and underground excavation schemes of river-crossing tunnel are further compared. The open excavation scheme of laminated structure is determined. Its construction is combined with the cofferdam by frames. According to the surrounding environmental conditions, a reasonable support system is adopted for the foundation pit, and the whole process of foundation pit excavation is simulated numerically. The results show that the influence of excavation on the surrounding environment meets the requirements of the code.