In the context of the grand construction of the new railway line tunnel project in Sicily, Italy, this article comprehensively and deeply analyzes the complex design and application of the man lock of tunnel boring machine in extreme pressure operating environments. Faced with the arduous task of long-distance crossing of full-section rock formations, especially the unique challenges brought by high-pressure water environments, this article creatively proposes a customized design scheme for the man lock system, aiming to completely solve the safety problem of pressurized entry operations. In response to the functional requirements of the man-lock during pressurized entry operations, and with due consideration given to ergonomics, emergency escape, environmental monitoring systems, etc., the man-lock system configuration was designed to provide equipment-related safety for workers. Finite element force analysis was carried out on the man-lock door and body to verify the structure's strength and ensure it meets working pressure requirements. The structure's stability and reliability were also confirmed through hydrostatic and air-tightness tests. The results of the finite element analysis and pressure tests show that the designed man-lock not only satisfies engineering needs, but also offers strong equipment support for the shield machine's efficient and safe tunneling, ensuring simultaneous enhancement of construction efficiency and safety.