Abstract: The fouling and slagging of boilers burning sodium-rich coal is extremely serious, which greatly limits the combustion, utilization and development of sodium-rich coal. In order to explore the capturing performance of sodium-rich coal ash for the sodium chloride in the flue gas, the sodium-capturing capacity of Hami coal ash and Wucaiwan coal ash was investigated. Inductively coupled plasma optical emission spectrometer（ICP-OES） was used to analyze the changes of the sodium content of the samples before and after the sodium-capturing experiment. To explore the sodium-capturing mechanism of the coal ash, the evolution rule of the mineral components during the sodium-capturing process of the coal ash was investigated using X-rays diffraction（XRD）. The results indicate that Hami coal ash shows good sodium-capturing performance at 810℃, the coal ash can capture sodium chloride vapor by physical adsorption and chemical reaction. With the increase of temperature, the physical adsorption capacity of H-900 decreases, and the sodium contained in H-900 will be released to the environment, resulting in the decrease of its sodium-capturing capacity. Wucaiwan coal ash has low silicon aluminum content and high calcium magnesium content, so it is unable to capture chloride vapor effectively through chemical reaction and physical adsorption. Wucaiwan coal ash is in a state of sodium saturation, so it has no ability to reduce the content of gaseous sodium compounds in the flue gas.