Since the International Convention for the Safety of Life at Sea (SOLAS) came into force in 1974, watertight doors and fireproof doors have become an indispensable and important part of sea-going ships as a means to ensure the safety of crew. The design of the large marine fireproof watertight doors has the higher requirements along with the gradual improvement in the design of cargo ships and large warships. An L-type marine low-threshold A-60 fireproof watertight door with high accessibility is designed for large ships, and the finite element analysis of the door leaf structure is carried out and used as a reference for the design of the large fireproof watertight doors.