Abstract: Zhundong coal in Xinjiang with the characteristics of huge reserves,low mining cost,high volatile yield and low sulfur content,is a high-quality power coal. However,due to high sodium content of Zhundong coal,ash sintering and depositing easily occur on the heating surface during its combustion process,resulting in the serious ash deposits and slagging,which greatly limits the development and utilization of the high sodium coal. Thus,to realize the clean and efficient utilization of high sodium coal,it is necessary to fully understand the sintering characteristics of high sodium coal ash. In this paper,the research progress on the ash depositing and slagging mechanism and ash sintering behavior of high sodium coal was summarized. Furthermore,the inherent relationship between the sintering characteristic and the fouling and slagging behavior of the high sodium coal ash was explored. During the combustion process,alkali metals( mainly sodium)in coal is released into flue gas in the forms of Na_2SO_4,Na Cl and Na,which contact with the heating surface and condenses onto it to form viscous inner white layer. The fly ash particles in the flue gas can be captured by the inner white layer and reacts to form low melting point compounds,and thus,the sintering temperature decreases,and the contamination-enhanced " contamination sintering" process on the heating surface of the boiler is promoted and accelerated. The sintering process of high sodium coal ash includes: solid state sintering,liquid phase sintering and gas phase sintering. The influencing factors on the sintering process of the coal ash include reaction temperature,ash composition,ash particle size,reaction atmosphere,additives,boiler design and boiler operating conditions,etc. The additives can be divided into basic oxides and acidic oxides according to the types of oxides. Basic oxides can reduce the sintering temperature of the coal ash,and acidic oxides can increase the sintering temperature of the coal ash to some extent. The future research focuses on the development of new and low-cost additives consisting of single or mixed compound,which can fix sodium matters in the flue gas or react with low-melting sodium-containing minerals in the ash to increase the sintering temperature of high sodium coal ash. Moreover,the influence mechanism of sodium vapor on the dynamic depositing and slagging characteristics should be further studied from the micro-level. The methods for the sintering temperature measurement of coal ash are also introduced,including thermal conductivity analysis method,pressure measurement method,thermomechanical analysis method,sieving method and pressure drop method. Among them,the pressure drop method is relatively accurate for the sintering temperature measurement so far. Laboratory for Clean Conversion of Carbon-based Fuels,USST has engaged in the research on the sintering and slagging characteristics of high-sodium coal ash,in order to provide some guiding meaning for the coal combustion and utilization process.