Abstract: The mixture of NH₃ with CH₄ can effectively improve the combustion performance of NH₃, and the effect of NH₃ addition on flame behaviours can be better understood through simulations. The article uses ANSYS for simulation research and conducts numerical calculations on the combustion of NH₃/CH₄/O₂ with different NH₃ addition ratios and different equivalent ratios. The results show that: the addition of NH₃ leads to a decrease in flame temperature, and the temperature core distribution region moves downstream of the flame with the increase of NH₃ addition ratio, while moving towards the root of flame with the increase of equivalent ratio; when the addition ratio of NH₃ increases, the peak content of OH* and CH* decreases, and the position of OH* peak moves downstream of the flame, while the position of CH* peak remains unchanged, but the radial position of CH* shows a multimodal distribution; When the equivalent ratio increases, the peak content of OH* and CH* rises, and the area of OH* distribution area increases, the peak position moves towards the direction of the flame root, and the CH* distribution area tends to be concentrated and moves away from the flame root, radial position still presents a multimodal distribution. In addition, chemical kinetic analyses show that the addition of NH₃ leads to a change in the OH* generation pathway, and the rate of production OH* decreases with the addition ratio of NH₃ increasing.