Morphological alloy of Nd4.5Fe76.3Ga0.3Co1.0B18 prepared by rapid quenching was crystallized to obtain the manocrystalline permanent magnetic materials in which Fe3B were the dominant phases. The X-ray diffraction method, the transmission electron microscopy technique and magnetic measurement were used to analyze the microstructure and magnetic properties of the nanocomposite materials. The relationship of the microstructure, the magnetic properties with the exchange coupling interaction between crystallites was studied by determining the δM curve of the nanocomposite magnets.