Abstract:The water above surrounding rock of subsea tunnel is of a stable water level with plentiful supply. The tunnel lining structure bears water pressure for long time. In design of lining structure,the water pressure should be identified firstly. The evaluation and calculation of tunnel cross-section layout,lining type and structure safety are carried out based on water pressure and water inflow. For Xiamen Xiang¢an subsea tunnel under construction,model test of the external water pressure feature under different drainage modes indicates that the water pressure on fully-enclosed lining should be not discounted. The water inflow in the tunnel is forecasted;and the lining is designed in fully-enclosed or limited drainage type since the drainage in operation stage can not be satisfied. The most economic and reasonable lining cross-section is obtained based on structure analysis and comparison under different lining sections with combination of water pressure and surrounding rock pressure by means of finite element software ANSYS. The recommended lining section is proven to be reasonable by both computing results and construction practice.