In order to explore the deformation characteristics and influence of the stratum when the shield tunnel is crossing the river, the finite element model of the shield tunnel crossing the river is established with the shield tunnel crossing Fengjiang river in the GX08-GX09 section of the second phase of the Guangdong east water resources optimization allocation project as the background. The deformation characteristics of the stratum and the change law of the segment displacement during the shield tunnel crossing the river are analyzed, as well as the influence of grouting pressure and face support force on the surface settlement and segment displacement. The research results show that before the shield tunnel passes through the river, the vertical displacement of the surface above the face in the excavation direction is settlement deformation, with a maximum value of 4.5mm ; the segment floats up with the uplift of the stratum, and the floating amount of the segment after grouting is about 27.4mm . During the process of crossing the river, the thickness of the overlying soil layer decreases, the vertical displacement of the surface is uplift deformation, with a maximum of 2.5mm ; the floating amount of the segment increases significantly, with a maximum value of 31.7mm . When the shield tunnel enters and exits the river section, the floating amount of the segment decreases to 24.5mm . As the grouting pressure and excavation pressure increase, the surface settlement directly above the shield tunnel gradually decreases, while the local uplift on both sides gradually increases, and the floating amount of the pipe segments increases. It is recommended that the excavation pressure be controlled at 0.28?0.30MPa and the grouting pressure be controlled at around 0.25MPa during the process of crossing the river.