For the purpose of utilizing fly ash from gasification of low rank coal, we performed the series of experiments such as pyrolysis and char-CO2 gasification on fly ash by using the thermogravimetric analyzer (TGA) at nonisothermal heating conditions (10, 20 and 30 ℃/min). Pyrolysis rate has been analyzed by Kissinger method as a first order, the reliability of the model was lower because of the low content of volatile matter contained in the fly ash. The experimental results for the fly ash char-CO2 gasification were analyzed by the shrinking core model, homogeneous model and random pore model and then were compared with them for the coal char-CO2 gasification. The fly ash char (LG coal) with low-carbon has been successfully simulated by the homogeneous model as an activation energy of 200.8kJ/mol. In particular, the fly ash char of KPU coal with high-carbon has been successfully described by the random pore model with the activation energy of 198.3 kJ/mol and was similar to the behavior for the CO2 gasification of the coal char. As a result, the activation energy for the CO2 gasification of two fly ash chars don’t show a large difference, but we can confirm that the models for their CO2 gasification depend on the amount of fixed carbon.