Abstract: The gasification reaction characteristics of coal chars with CO2 at high carbon conversion were investigated by means of an isothermal thermogravimetric analysis at ambient pressure and at temperatures from 1200℃to 1400℃. The effects of gasification temperatures, heating rate and pyrolysis temperature on the gasification reactivity of coal chars were examined. The gasification reactivity of rapid pyrolyzed chars is found to be higher than that of slow pyrolyzed chars, and the general gasification reactivity of chars increases with gasification temperature. The gasification rate of rapid pyrolyzed chars is almost the same at gasification temperatures from 1300℃ to 1400℃. In addition, the ranges of the average apparent activation energies of slow and rapid pyrolyzed chars at the carbon conversion between 90% and 98% are 59.64kJ/mol～105.92kJ/mol and 34.47kJ/mol～40.87kJ/mol, respectively, which indicates that the gasification reactions have been controlled by gas diffusion.