Hot blast stoves are important equipment used in the iron-making process. Its cyclic operating process consists of an on-gas period and an on-blast period. In this study, a 3D thermal and thermomechanical model of a hot blast stove were used to calculate the temperature and stress distribution during the operating process. The thermal analysis simulation results are compared with the in situ data, and the maximum error was found to be lower than 7%. The results indicated that the maximum principal stress mainly occurred outside of the refractory linings, and the minimum principal stress mainly occurred inside of the refractory linings. The maximum deformation occurred inside of the refractory linings in the combustion chamber. The shell is mainly subjected to the maximum principal stress, where the minimum principal stress only occurred at the junction. The maximum deformation of the shell occurred at the top of the combustion dome.