Blast-furnace gas produced from the process of iron making effectively can be used as fuel for engines to generate electricity for most middle and small steel enterprises. The effects of different component of blast-furnace gas, compressive ratio and ignition timing on combustion property of blast-furnace gas are simulated by GT-POWER software in this paper. The results show that flame speed and combustion rate will increase with the proportion of carbon monoxide and hydrogen increasing. There will be an optimized compression ratio value, under which the burning velocity is maximum. Within a certain scope, increasing ignition timing angle appropriately can improve property of combustion. A comparison of simulation and experiment result shows that the predictions give good results. All these results can help to optimize the parameters that affect the combustion, and provide certain reference for the further study blast-furnace gas engine.