Abstract: The general design proposal and key technologies of the Nanjing Weisan Road river-crossing tunnel project are introduced with respect to the engineering characteristics and difficulties encountered, such as a very large diameter, ultra-high water pressure, complex geological and environmental conditions, driving in high strength rocks, high-precision construction control and so on. By synthetically analyzing the original design options of the tunnel plane, longitudinal profile, cross-section and civil structures and studying the key technologies for survey and design, the optimized final design option is proposed so that the overall function and safety of construction and operation can be best achieved. This paper is a significant reference for improving the construction of large-scale highway underwater shield tunnels.