Abstract: Taking the Jiaozhou Bay Subsea Tunnel of Qing-dao Metro Line 1 as the research background, nine main influen-cing factors affecting the water pressure at the composite lining periphery are selected, and on the basis of using Midas finite element numerical analysis software, the significant influence levels of these nine factors on the water pressure reduction coefficient under two test levels are analyzed by using orthogonal test design method. The results show that: the significant factors affecting the water pressure magnitude at the secondary lining periphery are the radius of the secondary lining periphery，the ratio of surrounding rock permeability coefficient to the secondary lining permeability coefficient. The significant factors affecting water pressure at the initial support periphery is the ratio of surrounding rock permeability coefficient to grouting circle permeability coefficient, the grouting circle thickness, the ratio of surrounding rock permeability coefficient to secondary lining permeability coefficient and the tunnel radius, among which the ratio of surrounding rock permeability coefficient to secondary lining permeability coefficient has a significant effect on the water pressure at the peripheries of secondary lining and initial support. Therefore, during the design and construction of subsea tunnels, attention should be paid to the lining permeability performance，the design and selection of the support structure parameters to ensure the smooth excavation and operation safety of the subsea tunnel.