A domestic sea-crossing suspension bridge is a vital traffic artery connecting local islands. The massive transportation of flammable substances like LNG (liquefied natural gas) on the bridge poses a significant safety hazard to the operation of the bridge. This paper is based on existing oil pool combustion experiments in China, using the fire dynamics simulation software FDS and finite element analysis software ABAQUS to simulate LNG tanker fire and conduct the whole bridge mechanical analysis in the fire, in order to predict the structural impact of the LNG tanker fire and to provide reference for preventing and responding to emergencies of fuel tanker fire on the bridge. The simulation is aiming at a small probability fire accident of two LNG tankers rear-end burning in the middle of the main span of the bridge. The simulation results show that when an LNG tanker fire occurs on the bridge, the main cable and some slings are directly affected by the fire: the main cable loses part of the structural performance and two slings are damaged by heat and fail. In addition, the bridge deck pavement in high temperature area is also damaged by high temperature and the main beam steel structure under the pavement is relatively less affected by heat. The deflection of the bridge increases 0.234 m in the fire, and the forces on the east and west sides of the bridge are no longer balanced. According to the fire prevention research on key components in the high temperature area in the fire, the heat transfer analysis of ABAQUS shows that main components of the bridge can be effectively protected in the fire by the design of a double-layer 5 mm thick thermal insulation aerogel protective layer.