Abstract: Take a 320 t torpedo car as the research object, a three-dimensional heat transfer mathematical model was established with the Fluent software, and the temperature field of the body and the car shell under actual production conditions were simulated, in which non-linear change of physical parameters with the temperature change and the radiation was considered. The changing of temperature distribution of torpedo car inside lining with time and the effect of lining thickness on the temperature drop were analyzed. The results show that temperature of the external shell decreases with time increasing. In the initial state, the temperatures of vertebral body parts on both ends of car are higher than those of the middle parts. 14 h later, the vertebral body parts temperatures drop faster than those of the middle parts, which is because the lining thickness of the vertebral body parts on both ends of car is less than that of the middle, and the heat transfer is fast. The temperature drop is decreased gradually along the thickness from the inside to the outside. By comparing the measured temperature of the external shell and the calculated result, the two agree well, the maximum error is only 1.32%.