N + Cr ions were co-implanted into the carburized 18Cr2Ni4WA steel to improve hardness, wear and corrosion resistance. The microstructures of the samples were characterized by the glancing incidence X-ray diffractometer, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy, respectively. In addition, the mechanical, corrosion and tribological properties were evaluated by nano-indenter instrument, electrochemical corrosion workstation and wear test, respectively. The results showed that after implanting N + Cr ions, a new nano-nitride phase was formed on the surface of carburized steel. Ions implantation process was accompanied by the radiation damage, which led to lattice distortion on the surface of the steel. These changes accordingly made the N + Cr ions implantation layer present high nano-hardness. Meanwhile, the N + Cr ions implantation layer could effectively prevent the synergistic effect of corrosion and friction in seawater environment, and significantly enhance the tribological property of the carburized steels in simulated seawater.