Abstract: The steam gasification characteristics of Zhundong coal with additive CaO at medium temperature of 700-750℃ were investigated by Thermal Gravimetric Analyzer (TGA). The Brunauer-Emmett-Teller (BET) specific surface area of the coal char was tested by N₂ adsorption, and the different occurrence modes of alkali metals in the coal were analyzed by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). The results show that the soluble sodium could catalyze the gasification reaction effectively and the water-washed coal has the highest activity. The additive CaO and the inherent sodium have a synergistic effect during the gasification, and the optimal Ca/C molar ratio is 1.0. The kinetic parameters were calculated using the homogeneous model (HM), the shrinking core model (SCM) and the modified volumetric model (MVM), respectively. The results indicate that the MVM is better to represent the char steam gasification reaction, and its activation energy calculated by the MVM is 160.90 kJ/mol.