The work aims to fabricate metal plus nitride hard coatings on medium carbon steel substrates to study the service behaviors under the corrosive wear conditions. NiCoCrAlY/NiCoCrAlYN double layer coatings were fabricated on 42CrMo steel substrates by means of arc ion plating. The nitrogen content was manipulated by varying the nitrogen gas flow. The mechanical and corrosive wear behaviors were studied with microhardness tester and tailored corrosive wear apparatus, in combination with multiple analytical techniques such as XRD, XPS and SEM. The results showed that NiCoCrAlYN coatings were mainly composed of γ-Ni, γ‘-Ni3Al, fcc-CrN and fcc-AlN ceramic phases. With the increase of N2 flow rates, the contents of ceramic phases increased, followed by the promotion of the coating micorhardness from 575HV0.05 to 730HV0.05, as well as the degradation of the coating adhesion from HF 2 to HF 3. Compared with the NiCoCrAlY single layer coating, the NiCoCrAlY/NiCoCrAlYN double layer coatings exhibited better corrosive wear performance, which was increased with the increase of N flow rates. The coating revealed the best corrosive wear resistance when the N2 flow rate reached 400 mL/min. Moreover, the failure model of coating also converted from wear failure to corrosion failure. The nitride surface with the virtue of high hardness improves the coating wear resistance, and NiCoCrAlY-NiCoCrAlYN interface increases the coating corrosion resistance as a result of interface barrier effect. In addition, the NiCoCrAlY bottom layer exhibits excellent toughness and malleability. Because of the three effects mentioned above, the corrosive wear resistance of NiCoCrAlY/NiCoCrAlYN double layer coatings is significantly higher than that of NiCoCrAlY single layer coating.