Abstract: The influence of plasma chemistry on the ammonia synthesis reaction was explored by employing a dielectric barrier discharge plasma in this work. When the gas temperature was below 673 K, the average electron energy increased with the gas temperature, enhancing the activation and dissociation of N₂ and H₂, and thereby facilitating the synthesis of ammonia. When the temperature was above 673 K, a significant change occurred in the discharge mode, resulting in a sharp decline in NH₃ concentration and energy efficiency. Additionally, the thermal decomposition of ammonia was intensified with temperature. When the residence time was within the range of 0.9‒4.5 s, its increase was beneficial to NH₃ concentration and energy efficiency. When the residence time exceeded 4.5 s, the drop in gas temperature led to a decrease in average electron energy, which in turn resulted in a decline in NH₃ concentration and energy efficiency.