When a new torpedo car is developed, its thermo-mechanical stress must be analyzed carefully in order to guarantee its strength condition. This paper describes an investigation into the thermo mechanical behavior of the torpedo car using ANSYS software. A three-dimensional, coupling model of torpedo car has been established successfully. The analysis produces outputs such as the temperature distribution and coupling stress of this car. The influence of swell gap and refractory lining thinning are also discussed. The results indicate that the swell gap and entire thinning of refractory lining can reduce the stress remarkably, but the local thinning will increase the stress of this local zone.