Abstract: To understand the fire resistance of steel-concrete-steel composite structure and further provide the ba? sis for its structural design and fire protection, the multifunctional large refractory-lined test furnace which is independently developed was used for the fire resistance test of local full-sized elements in different fire protection schemes to research the law of heat transfer of the tube structure of steel-concrete-steel immersed tube tunnel at high temperature caused by a fire. The results show that fireproof plates can greatly protect the tube structure in a fire, and if no fireproof plates are used for protection, obvious voids in concrete will appear in the vertical position of elements; the temperature value at each measuring point on the unexposed surface of a fireproof plate regularly varies with the hearth temperatures, but they do not completely synchronize, and the temperature changes in the measuring point on the unexposed surface of a fireproof plate lag behind those of the hearth; the depth of temperature influence on the tube structure at high temperature caused by a fire reaches about 550 mm from the upper surface of bottom plate, and the height of heat transfer of the concrete section is about 400 mm.