The Ni-W-Er2O3 coating on 45# steel substrate was fabricated by electrodeposition. The microstructure and morphology of the composite coatings were analyzed by SEM, EDS and XRD, etc. At the same time, the thickness, microhardness and corrosion resistance of the coatings were measured by means of the magnetic thickness apparatus, microhardness tester and electrochemical workstation. The results show that the composite coating with a compact structure is not found to have obvious flaws and has a good adhesion with the matrix. The composite coating can obtain a high hardness, high tungsten content and better corrosion resistance with the addition of rare earth oxide Er2O3. When the addition amount is 16 g/L, the comprehensive performance of the coating is best.