This study describes the preparation of Ni−P− Cr 3 C 2 composite coatings using pulsed electrodeposition, with varying Cr 3 C 2 concentrations (0, 1, 2, 3, 4, and 5 g/L). Subsequently, the Ni−P−Cr 3 C 2 composite coatings are heattreated at different temperatures (200, 400, and 600 °C) using the characteristic of Cr 3 C 2 oxidizing to Cr 2 O 3 at high temperatures. The Ni−P coatings, Ni−P−Cr 3 C 2 composite coatings, and heattreated-state Ni−P−Cr 3 C 2 composite coatings are compared and discussed. The results show that the hardness, wear resistance, and corrosion resistance of the composite coatings are optimized when the Cr 3 C 2 content is 3 g/L and the heat-treatment temperature is 400 °C. This is due to the presence of oxides such as Cr 2 O 3 on the surface of the composite coatings after heat treatment at 400 °C. By efficiently enhancing the coating's densification to the substrate, these oxides raise the composite coating's resistance to corrosion and wear. The Ni−P−Cr 3 C 2 composite coating in its heat-treated makeup at 400 °C is found to have long-term corrosion resistance in the 3.5 wt % NaCl solution immersion test. This study provides a new idea in the field of corrosion.