Abstract: Fouling and slagging is one of the main problems in the operation of oxy-fuel combustion boilers. Due to the difference in radiant heat transfer and chemical properties of CO2 comparing to N2,the fouling and slagging on the inner wall of oxy-fuel boilers is more serious. In recent years,scholars carried out systematic analyses on the fouling and slagging of coal ash under the condition of oxy-fuel combustion,and obtained more detailed results. However,there is still a lack of research on the ash formation of pulverized coal combustion based on the characteristic elements and atmosphere under oxy-fuel combustion. In this paper,the key elements Ca,Na,Fe in pulverized coal slagging were selected as characteristic elements,and the oxides or hydroxides of characteristic elements were selected as additives. Shanxi Anthracite with Al and Si as main ash components was employed as the experimental coal to quantitatively study the influence of characteristic elements on high temperature ash formation characteristics of coal under oxygen enrichment. It has found by experiment that when the content of characteristic elements is higher,the reaction time of pulverized coal in an oxygen-enriched atmosphere is reduced by 20-50 min compared with that in air atmosphere,and as the oxygen concentration increases,the reaction time of pulverized coal gradually increases; the ash melting point of high Fe coal and high Na coal is about 150 ℃ lower than the benchmark coal,but Ca has no obvious influence on the deformation temperature of coal ash. At the case of oxy-fuel combustion,calcium aluminosilicate and mullite will appear in the high-Ca coal as the oxygen concentration increases,and aluminosilicate such as anorthite is formed,and the amorphous phase of Na and Fe is strengthened as the temperature increases. The Fe in high-Fe coal changes from oxide to ferric aluminosilicate as the oxygen concentration increases. As the temperature increases,the content of enstatite and magnetite increases. The content of calcium iron silicon oxide and calcium-iron-silicon oxide first increases and then decreases. The coal ash obtained from the low-oxygen combustion of high-Na coal mainly consists of nepheline. The increase of oxygen concentration causes the gradual conversion to form sodium silicate. As the temperature rises,the form of Na changes from stable acid salt to sodium silicate salt or other stable amorphous transformation.