Abstract: This work utilized molecular dynamics simulations to examine the influence of annealing temperatures from 700 K to 1700 K on the microstructure and mechanical properties of Fe₈₀P₂₀ metallic glass. Findings reveal that annealing temperature is pivotal in modulating the rejuvenation of metallic glass. At 1100 K, the sample's potential energy and free volume reach their maximum, showing a significant rejuvenation characteristic. With the increase in annealing temperature, the number of P atoms in the coordination number of P atoms decreases, resulting in reduced free volume. Aged samples displayed a higher prevalence of like–icosahedral structures, whereas rejuvenated samples contained a greater abundance of like–BCC clusters. Mechanical analysis indicated that aged samples had higher tensile strength but lower ductility compared to rejuvenated samples. Strain localization analysis demonstrated that samples annealed at 1100 K had the lowest strain localization, indicating more homogeneous deformation. These results offer a deeper understanding of how annealing temperature affects the microstructure and mechanical properties of metallic glass, providing a theoretical foundation for the rejuvenation and performance enhancement of metallic glasses.