Abstract: Nanocrystalline (nc) Ni-Co-Fe-P alloy coatings were synthesized by pulsed electrodeposition. The structure, surface morphology and composition of nc Ni-Co-Fe-P alloy coating were studied by XRD, TEM, SEM and EDS. The effects of alloying with phosphorus and subsequent heat treatment on the wear resistance of nc Ni-Co-Fe-P alloy were studied using a friction-wear tester. The results indicate that the grain size of nc Ni-40.41%Co-6.16%Fe-1.63%P alloy coating was only 8.3 nm, and the hardness and wear resistance of nc Ni-Co-Fe-P alloy were higher than that of nc Ni-Co-Fe alloy coating. The hardness and wear resistance of nc Ni-Co-Fe-P alloy were improved by heat treatment. There was a positive relationship between the wear resistance and hardness, and the wear mechanism changed gradually from abrasive and adhesion wear to abrasive wear with increasing hardness of nc Ni-Co-Fe-P alloy.