Nanocomposite NdFeB magnets were prepared by melt-spun and crystallization annealing. Effects of Co and Zr addition on the crystallization behavior, microstructure and magnetic properties of the magnets were investigated. Results show that Co addition decreases the precipitation temperature of crystalline phases and increases the remanence. After further addition of Zr, the crystallization behavior changes from a two-step to a single-step process, the coercivity is increased markedly and the grains are refined. The exchange coupling interaction between the soft magnetic phase and the hard phase is enhanced obviously; as a result, the Nd9.5Fe76Co5Zr3B6.5 alloy exhibits excellent overall properties, i.e. Jr＝0.93 T, iHc=687 kA/m and (BH)max＝129 kJ/m3.