Abstract: Ammonia fuel utilization is an important means of energy low-carbon transition, moderate & intense low oxygen dilution (MILD) combustion technology can effectively improve the combustion efficiency of ammonia fuel and reduce emissions. Based on a self-built 20kW combustion furnace, an experimental study is carried out on NO_x emission characteristics of NH₃/CH₄ mixed fuel in MILD combustion mode, focusing on the influence of ammonia ratio, equivalent ratio and furnace inner wall temperature on NO, NO₂ and N₂O emission, and systematic comparison is made with the traditional swirl combustion mode. Studies demonstrate that compared with traditional combustion, MILD combustion can effectively reduce the emission of NO and NO₂ in ammonia fuel combustion, but N₂O emission occurs in MILD combustion. NO emissions peak at an ammonia ratio of 35%~40% and an equivalence ratio of 0.8, exhibiting a linear increase with wall temperature. With the increase of ammonia ratio and the decrease of wall temperature, the emission of N₂O gradually increases. At 1000K wall temperature and 55% ammonia ratio, the emission of N₂O reaches 40×10⁻⁶. In MILD combustion of ammonia fuel, coordinated control of N₂O and NO emissions is essential for effective NO_x reduction.