The blast furnace is a metallurgical reactor whose goal is to produce pig iron. The fuel / reductant in the reduction of iron ore in the blast furnace process, represents more than 50 percent of the cost of the iron. In order to increase the productivity of the blast furnace and reduce fuel consumption / reducer injection techniques are employed by tuyeres of materials that act as fuel / reducer. The combustion of natural gas injected into the tuyeres produces large amounts of hydrogen, which replaces part of the carbon monoxide as reducing gas in the tank. The hydrogen gas is better compared to the reductant carbon monoxide, because it has reaction rate with the iron oxides and, moreover, the CO2 generation in the process of reduction is decreased when compared to the use of pulverized coal (PCI), which is currently the material most commonly used injection by tuyeres in Brazil. This paper proposes the simulation of combustion of natural gas injected into the tuyeres of a blast furnace, using the CHEMKIN software package. Simulations from this software are widely used for optimization of combustion, which can quickly explore the impact of design variables on the performance of the process, using accurate models of chemical kinetics. The computer simulation results from the combustion of natural gas at typical conditions of blast furnaces allowed the prediction of the adiabatic flame temperature and the reaching of the reducing gases of iron oxides: H2 and CO. From the variation of process parameters was possible to obtain useful results in order to control and optimize the process.