Combustion reaction is the most important way of coal conversion，coal’s combustion parameter plays an important role in evaluating its ecological and economic indicators.The combustion characteristics are studied in this paper on six types of different rank power coals by thermogravimetric and fourier transform infrared spectrometry technique，respectively.The results show that each characteristic temperature and the temperature at which these gases，such as CO，CO2 and H2O released，become small with the decrease of the coal rank，contrarily weight loss of lower rank coal sample between each characteristic temperature increases.CO is generated at a lower temperature while CO2 is mainly generated at a higher temperature.Both the variation of activation energy and the reaction order pass a maximum as the temperature increases in the combustion process.All the above observations indicate that lower rank coal is easier to combust than higher rank coal.