Melt‐spun ribbons of Nd‐Fe‐Co‐B‐C system alloys were prepared by the single roller rapid‐quenching method. The effects of composition, substrate surface velocity, and heat treatment on the magnetic properties were studied. A maximum energy product of 140.5 kJ/m3was obtained for Nd11Fe72Co8(B0.5C0.5)9alloy ribbon prepared at a substrate surface velocity of 17.1 m/s. The amorphous Nd11Fe72Co8(B0.5C0.5)9ribbons prepared at a substrate surface velocity of 20.7 m/s were crystallized by heat treatment, and the optimum annealing condition was found to be at 600 °C for 30 min. Then the value of (BH)maxwas 138.5 kJ/m3. The value of (BH)maxfor a Nd11Fe72Co8(B0.5C0.5)9bonded magnet prepared by using the ribbons heated at 600 °C was 90.4 kJ/m3.