Abstract: A swirl spray burner is used to measure and analyze the flame structure, chemiluminescence signals of OH* and NH₂*, flame spectra and pollutant emissions during combustion, while examining the effects of varying methane, ethanol and ammonia mixture fuel composition and atomizing air-to-liquid ratios (ALR) on combustion and the trends of NO, NO₂ and CO emissions. Even though the use of ammonia results in high NO_x emissions, the use of ternary blends for co-combustion, especially when ethanol mole fraction is high, the CO and NO emissions can be reduced. Within the equivalence ratio of 0.45~0.70, increasing the ALR results in more complete spray atomization, which promotes mixing of fuel vapour with gas, leading to improved combustion and subsequently reduced CO emissions. The use of ternary blends and control the combustion parameters are measures that enable effective ammonia combustion, which serves as a guide for pollutant emission reductions and ammonia utilization for the industries.