Due to weak magnetism and poor pelletization performance of the mixed magnetite-hematite iron concentrate，the traditional air atmosphere preheating-roasting process often leads to insufficient pellet strength and high energy consumption. Oxygen-enriched roasting technology offers a new approach to this problem. In this study，the mixed magnetite-hematite iron concentrate was used as the raw materials to conduct a preheating-roasting process test on preheating and roasting pellets under varying oxygen volume fractions. By systematically adjusting key parameters such as roasting temperature， oxygen volume fraction， and roasting duration， and combining compressive strength tests， ferrous iron content detection and microstructure analysis，the effect law of oxygen-enriched atmospheres on pellet properties were comprehensively evaluated. The results show that under 40% oxygen-enriched conditions，a preheating temperature of only 800 ℃ is required to achieve a preheated pellet compressive strength of 600 N/P，representing a 100 ℃ reduction compared to air atmosphere. When the roasted pellet compressive strength reaches 3 300 N/P，the 40% oxygen-enriched condition reduces the roasting temperature by 50 ℃ compared to air atmosphere，while simultaneously decreasing the FeO mass fraction of pellets to below 3%，which reduces over 40% compared to air atmosphere. Through enhancing the oxidation reaction， the oxygen-enriched preheating-roasting process effectively reduces thermal energy consumption of pellet，and reduces pollutant emissions(e.g.，SO₂，NO_x) during roasting. This process not only aligns with the green andlow-carbon development goals of the iron and steel industry but also provides technical support for the efficient utilization of refractory iron ore resources.