Electric rotary kiln is one of the key equipment in the chemical industry, which is mainly used for heating materials. In the current research, the heat calculation method of the electric rotary alumina kiln is constructed, and the heat transfer processes in the furnace, the furnace tube, and the furnace tube wall are systematically analyzed. The theoretical model of the electric rotary alumina kiln is established and solved by the fourth-order Runge–Kutta method, and the temperature rise curves in the kiln are obtained. The numerical simulation is carried out to investigate the temperature distribution of materials and gases in the furnace tube. It is revealed in the results that the temperature distribution of the electric rotary alumina kiln is more uniform than that of the internal rotary kiln, and the stable operation state can be reached in a very short time, which means that reduced furnace tube length and reduced production cost can be achieved under the same roasting requirements.