Abstract: The effects of K₂CO₃， Fe₂O₃ on catalytic combustion reactivity of different rank fuels such as lignite, bituminous coal, anthracite and graphite were investigated by a synthetical thermal analyzer. The results show that the type and content of catalysts, particle size and rank of fuel are important factors influencing catalytic combustion. When K₂CO₃ and Fe₂O₃ were added, ignition temperature of anthracite decreases from 458℃ to 319℃ and 405℃, respectively. And its combustion rate increases from 11.94%/min to 26.40%/min and 17.66%/min, respectively. There are not evident effects of K₂CO₃， Fe₂O₃ on decreasing ignition temperature of lignite and bituminous coal, but ignition temperature of anthracite and graphite decreases remarkably. With increasing rank of fuel, extent of decreasing ignition temperature is enhanced. Due to different factors led to changes of ignition temperature and combustion rate which changes are different too when catalyst is present.