Abstract: The geological conditions of submarine shield tunnel between Haicang Avenue Station and Dongdu Road Station of Xiamen Metro Line 2 are very complex, where the soil and water pressure are large, and there are a large number of solitary stones and raised bedrock. Construction is highly difficult, and the cutter head is easy to wear and collapse, which requires changing the knife with ballast frequently. In order to solve the problem that the excavation surface is prone to instability under the complex geological conditions of the seabed, pressure holding technology of the submarine shield under different geological conditions is studied. Pressure-keeping technology of submarine shield under different conditions, such as single stratum, fractured stratum, fractured strong permeable unstable stratum is put forward. Construction risks are effectively avoided and controlled, ensuring smooth completion of the project.