Abstract: To investigate the influence of ultrasonic vibration on the Nd-rich phase distribution in hot-deformed Nd–Fe–B magnets, the MQU-F type melt-spun powders were used to prepare hot-deformed Nd–Fe–B magnets through hot pressing and hot deformation processes with ultrasonic vibration applied during the hot deformation stage. The deformation stress during the conventional and ultrasonic-assisted hot deformation processes of the magnets was analyzed by Abaqus software. The distribution and composition of the Nd-rich phases were examined by scanning electron microscope and energy disperse spectroscope, while the magnetic properties at the central region and the boundary region of the magnets were detected by the MPMS3 magnetic property measurement system. The results show that, after applying the ultrasonic vibration, the deformation stress of the magnets is reduced due to the acoustic softening effect, leading to a 22.3% decrease in the compressive stress on the melt-spun ribbons and a significant reduction in the extrusion of the Nd-rich phases from within the ribbons. Consequently, the diffusion channels of the Nd-rich phases between adjacent melt-spun ribbons and neighboring grains are widened. Influenced by the proportion of the Nd-rich phase region and the diffusion channels between adjacent grains, the aggregation region of the Nd-rich phases within the melt-spun ribbons changes. Under the acoustic streaming, the Nd-rich phases in hot-deformed Nd–Fe–B magnets are subjected to the equivalent force from acoustic pressure, causing the concentrated distribution region to diffuse from the central section of the magnets toward the lower end face. When the ultrasonic power ranges from 0 to 47 W·cm⁻², the higher ultrasonic power results in the greater equivalent force from the acoustic pressure, making the Nd-rich phases more prone to accumulation at the lower end face of the magnets. Due to the widening of the diffusion channels of the Nd-rich phases between the adjacent melt-spun ribbons, the Nd-rich phases are more uniformly distributed along the radial direction of the magnets, resulting in the significant enhancement of coercivity, with increases of 25.4% and 30.9% observed at the center and edge of the hot-deformed magnets.