Although the direct reduction of iron ore with hydrogen is regared as an important technological approach for the steel industry to achieve low-carbon development, it shows great potential in reducing energy consumption and enhancing efficiency. However, its application in industry is limited by certain deficiencies in its process theory in the presence. The structural evolution of iron ore pellets during the hydrogen metallurgy process can be changed by adjusting process parameters such as ironmaking temperature, which will impact the reduction behavior as a whole. To uncover the microscopic mechanisms related with the effect of temperature on the process of direct reduction iron-making, therefore, the pure hydrogen reduction of iron ore pellets at 600 ^oC to 900 ^oC was examined in terms of the reduction thermodynamics and microstructural evolution of pellets. The findings reveal that, thermodynamically, the Fe₂O₃→Fe₃O₄ reaction stage required substantially lower demand for the diffusion to of the reducing agent H₂ and the diffusion away of the reaction product H₂O in contrast to the Fe₃O₄→FeO and FeO→Fe reaction stages. Increasing the temperature can improve the overall reduction degree of the pellets by strengthening the thermodynamic driving force for the Fe₃O₄→FeO and FeO→Fe stages. The number and size of pores in the pellets increase with temperature, which improves the diffusion driving force and shortens the diffusion channel for the reduction reaction. The nucleation and growth of Fe exhibit distinct characteristics as the temperature increases from 800 ^oC to 900 ^oC, but the reduction efficiency shows only a slight enhancement. This work is important for optimizing the process of hydrogen direct reduction of iron ore pellets, from a theoretical and practical standpoint.