Fe69.5−xNd7B21Nb2.5Zrx (x = 0–3) permanent magnets were produced by annealing bulk amorphous alloys. The intrinsic coercivity (Hcj) as well as maximum energy product ((BH)max) were enhanced significantly by Zr substitution in the Fe69.5−xNd7B21Nb2.5Zrx (x = 0–3) alloys, while the remanence (Br) is reduced slightly. When x = 2, annealed magnets tend to display the optimal properties of Hcj = 513.92 kA/m, Br = 0.57 T and (BH)max = 37.59 kJ/m3. The effects of the magnetic field intensity on the distribution of elements, microstructures and hard magnetic properties in Fe67.5Nd7B21Nb2.5Zr2 magnets were investigated. The results of X-ray diffractometry, transmission electron microscope and atom probe tomography indicated that the magnetic field heat treatment can not only contribute to a uniformly distributed B element enriched region but also benefit the precipitation of α-Fe. After heat-treatment at 563 K × 1 T, Hcj, Br and (BH)max experienced an increase from 513 kA/m to 583 kA/m, 0.57 T to 0.65 T and 37.59 kJ/m3 to 50.05 kJ/m3, respectively. Thus, the Hcj, Br and (BH)max are enhanced by 14%, 14% and 33%, respectively.