Ammonia can be used as a zero-carbon fuel to replace part of coal for co-firing process, which can effectively reduce the original pollutant emissions of power plants and promote the transformation of coal-fired power plants to coal and ammonia co-firing powerplants. However, due to the high nitrogen content in ammonia, the problem of NOx emission has attracted much attention. In the complex coal and ammonia co-firing process, the correlation between NOx emissions and coal ash is also worthy of further exploration andanalysis. High-alkali coal in coal-fired power plants is a kind of coal with broad development prospects, but the emission characteristicsof high-content metal oxides on ammonia oxidation reaction are rarely studied. In order to explore the influence of different kinds of high-alkali coal ash on the emission characteristics of ammonia oxidation reaction during the coal and ammonia co-firing process, an ammoniaoxidation reaction test platform was built to analyze the variable working conditions, and the two indexes of NH3 conversion rate andNO generation rate on the surface of various types of coal ash at different temperatures were compared. The specific influence of various metal oxides in coal ash on the emission characteristics of ammonia oxidation reaction was expounded from two aspects of test resultsand reaction mechanism. The results show that the main metal oxides CaO, MgO and Al2O3 in coal ash can promote the gas-solid ammonia oxidation reaction on the surface of coal ash during the coal and ammonia co-firing process, and improve the NH3 conversion rate. At400-600 ℃ , the promoting effect of coal ash on the conversion rate of NH3 is as follows: HM-2>HM-1>CJ>AKS>EERDS, which corresponds to the order of CaO content in coal ash from high to low, which is basically consistent with the order of MgO. In addition, the abovethree kinds of metal oxides can promote the directional conversion of NH3 to NO, and the catalytic effect of CaO is the most significant.Among them, the selectivity of HM- 2 with the highest Ca content to NO formation can be increased by 67.86% compared with thepure gas phase ammonia oxidation reaction. CaO and MgO can promote the oxidation of NH3 and NO on the catalyst surface, which is conducive to the rapid production of N2O the advance of N2O formation temperature. However, the presence of Na2O and Fe2O3 has an inhibitory effect on the oxidation reaction of NH3, and it has excellent performance in promoting the reduction of NO by NH3. Among them,the mechanism of Na2O and Fe2O3 promoting NO reduction is not the same.