Today, among the various methods of iron oxide reduction, direct reduction methods, including the carbothermal reduction method, have been favored by industries around the world due to their advantages such as low energy consumption and low pollution compared to other reduction methods. In the present study, a mathematical model is developed to simulate the kinetics of the reduction reaction of iron oxide dust and carbon composite pellet in a rotary hearth furnace and consequently, investigate the behavior of the process in variations of the pellet carbon content. The model results were in a good consistent with experimental results. Calculating results showed that with increasing the C/O ratio that was varied from 0.5 to 2.53, the temperature profile inside the pellet forms in a shorter time due to the increase of effective thermal conductivity of the composite and consequently reaction zones start sooner. As it was seen , the percentage of deoxygenation for a change in carbon content of 0.5 to 2.53 increased from 0.27 to 0.71, respectively. Since there is a carbon lost through exiting the gases from the pellet; stoichiometric ratio of C/O cannot complete the total metallization of the iron oxides. Therefore, the C/O ratio higher than unity is required for completion of reduction.