In order to beter understand the smelting characteristics of sinter in a hydrogen-enriched carbon recycling oxygen blast furnace （HyCROF）,in this study experiments were conducted on the reduction degradation, reduction behavior,and softening-melting performance of sinter under different reducing atmospheres. The experimental results show that at a reduction temperature of 500 ℃ compared with a traditional blast furnace,the low-temperature reduction degradation index （>6.3 mm)、（>3.15 mm) of the sinter under HyCROF carbon recycling conditions decrease by 58.6% and 37.7%,respectively. Compared with HyCROF carbon recycling,under the HyCROF carbon recycling+20% H₂ atmosphere,the low-temperature reduction degradation index （>6.3 mm)、（>3.15 mm) of the sinter increase by 21.3%and 10.2%,respectively,indicating a significant improvement in sinter reduction degradation. At a temperature of 1 100 ℃,the reduction degree of the sinter under HyCROF carbon recycling conditions is obviously improved. Compared with the traditional blast furnace,the metallic Fe content inside the sinter under both HyCROF carbon recycling and HyCROF carbon recycling + hydrogen-enriched conditions increases significantly,indicating that the highly reducing hydrogen-enriched atmosphere is conducive to the increase of the metallic iron phase of the sinter. Under the hydrogen- enriched carbon recycling atmosphere,the softening starting temperature of sinter decreases,the softening interval widens, while the melting starting temperature increases,and the melting-dripping interval narrows.