The provisions of different classification societies on the reduction of mechanical properties of steel under high temperature are introduced. The relationship between thermal stress and axial restraint stiffness is analyzed. The optimization method of structure design for the pipes carrying high-temperature fluid and the pipe rack structure is presented. The cause of the deformation of the transverse bulkhead stiffener flanges of a Floating Production Storage and Offloading (FPSO) is analyzed. The effect of heat stress on the structure design of high-temperature compartment should be considered. The effect of high temperature on corrosion protection of steel structure coating and sacrificial anode is discussed. The influence of high temperature on corrosion protection design of offshore structure should be treated reasonably.