Simplification of the detail reaction mechanism is critical to the numerical simulation of BFG (Blast Furnace Gas) combustion. The software CHEMKIN was used for solving a one-dimensional mathematical model of steady-state premixing combustion. By analyzing the effects of BFG’s basic species on the burning rate, the simplified reaction mechanism was obtained. Compared the results of simplified mechanism with that of detail mechanism, the consumed time of the former was less than 1 second but that of the latter was about 18 seconds. The differences between the molar fractions of BFG species which were computed by the two mechanisms were less than 0.4%. Therefore the reliability of the simplified reaction mechanism is verified.