The permanent magnetic nanocomposite PrNdFeB/Fe7Co3 ribbons were prepared by directly quenching, and the micro-structure and magnetic influence of composite materials with Co substitution were studied. The phase identification and the magnetic properties were measured by X-ray diffraction (XRD) and vibrating sample magnetometry (VSM).Microstructure observation was performed using scanning electron microscopy (SEM). The crystallization temperatures of the hard magnetic phase and the soft mag-netic phase were measured using differential scanning calorimetry (DSC). The experimental results showed that Co addition im-proved the Curie temperature of magnets. When the ribbons were melt-spun at 35 m/s, the added content of Co was 4 at.%, and the magnetic properties were the best, which were remanence (Br) of 0.379 T, coercivity (Hci) of 344.4 kA/m, the maximum magnetic en-ergy product (BH)max of 32.6 kJ/m3. Besides, the activation energy of each phase was calculated by Kissinger equation, which was 310.4 kJ/mol of Fe7Co3 phase and 510.2 kJ/mol of 2:14:1 phase, respectively.