Two typical Chinese high-rank coals with different iron contents, ZX coal from Zhenxiong, Yunnan province, and LY coal from Huaibei, Anhui province, were selected to Study the effect of iron on ash behaviors at a high temperature in a reducing atmosphere. Two iron,bearing minerals (FeS2 and Fe) were added to coals to change the C value (Fe2O3/CaO) and prepare :different series of ash slag samples: X-ray fluorescence (XRP) spectrometer, X-ray diffractometer (XRD), and FactSage Were employed to study the chemical composition, crystal mineral compositions, and mineral- transformation process. The effect of iron-bearing minerals on the liquidus temperature (LT) and C value of the liquid phase in slag system was discussed. The results show that two intermediates, iron carbide (Fe3C) and ferrosilicate (Fe2.56Si0.44O4), are found in slag, samples when FeS2 was added-to LY and ZX coals. The diffraction peak intensity of Fe3C decreases with the temperature increasing from 900 to 1000 degrees C, and that of Fe2.56Si0.44O4 decreases from 1200 to 1300 degrees C However, neither of the two minerals is found in slag samples with the addition of iron powder in coals. In comparison to that of the raw cog slag, the LT calculated by,FactSage software of each Slag sample decreases with the addition of iron-bearing minerals. The more the high-melting-point mineral is crystallized, the higher the LT. As iron-bearing mineral and/or calcium-bearing mineral behaviors (melting; transforming, Or crystallizing) change with the temperature increasing, a complicated nonlinear correlation between the C. Value and slagging temperature is obtained.