A mathematical model was established, which is a three-dimensional and steady-state heat transfer and flow process mathematical model in top combustion stove. Then the temperature field and velocity field were obtained according to the model. Based on these, the temperature and velocity fields were discussed under the conditions of various air and gas inlet position. The results show that when the gas entrance in single-channel mode, the liquid's temperature and velocity distribution was uneven extremely and tilted toward the furnace wall of gas entrance side in the hot blast stove. On the other hand, when the air and gas entrance in interval mode, the liquid's temperature and velocity distribution is uniform, and this mode is beneficial to the top combustion stove to work steadily.