This study elucidates the impact of the types and blending ratios of low-carbon alkanes (methane and ethane, C1/C2) on the combustion and emission performance of NH₃ and analyzes the reasons for the differences in the effects of C1/C2 from the elementary reaction. The experimental and numerical analysis results show that C1/C2 reduces the temperature dependence of NH₃ oxidation and promotes the formation of combustion-promoting (CP) radicals. The concentration of CP is determined by the strength of the H-abstraction reactions of C1/C2. The initial H-abstraction product of C1, CH₃, exhibits reaction inertness, whereas the inert radicals of C2 (C₂H₄, C₂H₃, and C₂H₂) appear after three main H-abstraction steps. Additionally, C1/C2 intensifies the NH→N→NO reaction, worsening thermal-NO emissions; this study classifies it as a thermal-NO generation pathway. Although NH₂ and NH significantly reduce fuel-NO, their effect on thermal-NO is less pronounced. The consumption of thermal-NO primarily depends on the reverse direction of the reaction N2+ON + NO.