Abstract: Thermal decomposition kinetics of limestone (900 μm) was investigated by using thermogravimetric and differential scanning calorimeter (TG-DSC) analysis. Based on the thermogravimetric experiment data, thermal decomposition kinetics parameters of limestone were calculated by Coats-Redfern method, Flynn-Wall-Ozawa method and Kissinger method. The results show that the activation energy (E) is 193.98 kJ/mol, and pre-exponential factor (lgA) is 8.81 min^-1. The reaction mechanism of limestone was further discussed by Malek method. It indicates that the reaction is a three-dimensional phase boundary reaction (R3) and the kinetic equation of limestone is obtained.