The work aims to improve tribological properties of 40Cr gear with high load at low speed. Nitrided layer and CrN coating were prepared on 40Cr steel substrate by plasma nitriding and arc-evaporation deposition (AED). Phase composition, morphology and tribological properties of 40Cr steel receiving different surface treatments were investigated with X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy dispersive spectrum (EDS) and reciprocating friction and wear tester. Thickness and microhardness of the nitrided layer was 10 μm and 558HV, respectively. The thickness and microhardness of the CrN coating was 4 μm and 1341HV, respectively. Wear rate of the 40Cr steel was 104.17×10-6 mm3/(N?m) under the load of 60 N, and the wear mechanism was mainly slight adhesive wear and abrasive wear; the wear rate of the CrN coating on 40Cr steel was 17.36×10-6 mm3/(N?m) under the load of 60 N, and the wear mechanism was mainly slight abrasive wear. The 40Cr steel exhibits the best anti-wear and anti-friction properties under the normal load of 20~60 N after CrN coating is prepared.