Iron is an important element commonly found in coal minerals, and its occurrence parameters such as content and valence arethe key factors affecting the physical and chemical properties of coal gasification ash, such as mineral transformation, melting, crystalliza⁃tion, viscosity, rheology, etc. The type of coal used in gasifier and the change of operating conditions (atmosphere and temperature) af⁃fect the occurrence form of Fe, and the coal gasification ash containing iron shows different physical and chemical properties, which isof great significance to guide the smooth slagging of gasifier. Research progress on the occurrence form of iron in gasification ash, meltingproperties of Fe on coal gasification ash, crystallinity and viscosity-temperature properties during cooling process were reviewed. Fe mainlyexists in raw coal in the form of FeO, Fe2O3, FeS, and FeS2, and is converted into iron-containing aluminosilicates during coal gasifica⁃tion, which is significantly affected by gas compositions (CO/ CO2 / O2 / H2), chemical compositions and temperature. Due to Fe3+ has astrong polarity, it is difficult to react with other minerals, and the melting temperature of ash slag in oxidizing atmosphere is higher. WhileCO, H2 and other reducing gases have strong reducibility, Fe2O3 in ash slag is reduced to ferrous (Fe2+), its melting temperature is re⁃duced, but reduced to metallic iron (Fe), it has a high melting point characteristic, ash melting temperature increases. The effects of Fein coal gasification ash on the crystallization properties of molten liquid slag during the cooling process include the types of Fe-contai⁃ning crystals, crystallization temperature, crystallization conditions, crystal morphology and scale. Among them, the interaction of Fe andCa in aluminosilicate network structure is significantly affected by atmosphere, temperature and chemical composition. The main effect isthe interaction between the transformation of Fe/ Fe2+ / Fe3+ and calcium feldspar minerals, which affects the transformation of iron-contai⁃ning crystals and the precipitation of iron. The effect of Fe on the viscosity - temperature and viscosity - temperature characteristicsof coal gasification slag was discussed, including the variation of viscosity and the critical viscosity temperature, the different valencestates and contents of Fe were important parameters in the process of viscosity change and melt structure transformation. Finally, the effectof Fe on the physical and chemical properties of coal gasification ash was summarized. It is expected that the combined physical and chem⁃ical effects of iron elemental and ionic state ( Fe2+ / Fe3+ ) in complex atmosphere ( H2 / CO/ CO2 ) on mineral conversion, ash meltingand crystallization are the key to clarify the role of iron in coal gasification ash. It is necessary to establish a suitable prediction system forthe properties of iron coal gasification ash and slag to provide guidance for the operation of industrial gasifier.