Ammonia-reduced hematite is a potential environmentally friendly ironmaking method，which is beneficial to solve the logistics and energy problems faced by the transportation and storage of hydrogen. However，the sample mass of ammonia-reducing pellets in previous researches is usually only 2. 8 g，and there is a lack of discussion on the activation energy of ammonia-hydrogen co-reduced pellets. In order to further analyze the reduction kinetics of NH₃ -H₂ reduced pellets，50 g pellets are used for reduction experiments，and the dynamic behavior of NH₃ -H₂ reduced pellets is discussed， and the phase structure composition and changes of NH₃ -H₂ pellets are studied by thermodynamics and XRD analysis. The results show that the rate of reduction of 50 g pellets with 100% NH₃ is less than that of a mixture of 50% NH₃ and 50% H₂ ，and the latter is less than 100% H₂ . With the increase of temperature，the reduction effect of 50% NH3 and 50% H₂ on pellets gradually approaches 100% H₂ . The shrinkage cylindrical model in the phase boundary control model is selected as the most general reaction mechanism function from the common mathematical models of gas-solid reaction， and the activation energies of 100% NH₃ ，50% NH₃ ，50% H₂ and 100% H₂ are 65. 42 kJ/ mol，54. 37 kJ/ mol and 29. 17 kJ/ mol， respectively. The decomposition reaction of NH₃ has a negative effect on the reduction of Fe₂O₃ . The results of thermodynamics and XRD analysis show that a small amount of Fe₄N is formed during the reduction of Fe₂O₃ by 100% NH₃ ，and the formation of Fe₄N is greatly reduced by reducing pellets with 50% NH₃ and 50% H₂ due to the difference between the partial pressure of NH₃ . The results can expand the research scope of ammonia reduction pellet dynamics and provide a theoretical basis for subsequent industrial applications.