Abstract: 【Objective】 Fe-P binary soft magnetic alloys have shown great potential in various fields of new energy, information, transportation, aerospace due to their high magnetic permeability and low coercivity. However, the addition of phosphorus leads to a reduction in the saturation magnetic induction（B_S） of Fe-based soft magnetic materials. Usually, iron-based soft magnetic materials are fabricated using powder metallurgy processes, and the enhancement of their performance is primarily achieved through the optimization of powder processing and sintering techniques. By modifying the sintering atmosphere, it becomes feasible to adjust the density and microstructure of the products without affecting the front-end processes, thereby potentially improving the magnetic properties of soft magnetic materials. This study therefore aims to demonstrate the influence of sintering atmosphere on the magnetic properties of Fe-0.45%P（mass fraction） based soft magnetic materials（FY-4500）. 【Method】The green compacts of FY-4500 rings, supplied by We-Transcend Suzhou Precision Machinery Co., Ltd., were obtained by uniaxial cold pressing of the insulated-coated FY-4500 powders that were purchased from Höganäs（China） Co., Ltd.. Then, these compacts were sintered at 1 125 ˚C in two distinct atmospheres, which were nitrogen-rich atmosphere（10%H₂+90%N₂） and industrial decomposed ammonia atmosphere with extra nitrogen（25%H₂+75%N₂）, respectively. After sintering, the magnetic performance as well as the microstructures and phase composition of these FY-4500 rings were characterized. 【Result】 The FY-4500 ring sintered in the nitrogen-rich atmosphere（NR ring） achieves a saturation magnetic induction（B_S） of 1.51 T and a coercivity（H_C） of 115 A/m. These values represent improvements of 10% and 36%, respectively, over those of the industrial ring sintered in the decomposed ammonia atmosphere（IN ring）. The phase composition, crystallinity, and intra-ring microstrain of two types of rings are quite similar, indicating that the influence of sintering atmosphere on these factors can be considered negligible. On the other hand, both metallographic microscope images and SEM images reveal significant differences in the microstructures of these two types of rings: the NR ring exhibits greater density and larger grain size compared to the IN ring, resulting in a higher B_S and a lower H_C for the NR ring.【Conclusion】The observed enhancements in magnetic properties can be attributed to the larger density, fewer structural defects, and larger grain size resulting from the sintering process in the nitrogen-rich atmosphere.