The work aims to study the effect of temperature and time of ion nitriding on the structure, surface hardness and wear resistance of nitriding layer of 4Cr5MoSiV steel, and to obtain the optimum technological parameters for improving wear resistance and hardness. The surface of 4Cr5MoSiV steel was treated by ion nitriding with the nitriding temperatures of 450, 480, 510 and 540 degrees, and the holding time of 5, 10, 15 and 20 h, respectively. The penetration depth and surface hardness were measured by micro Vickers hardness tester. The phase composition was measured by XRD. The wear resistance of the samples was evaluated by friction and wear tester. The wear scar area was observed by scanning electron microscopy. The phase composition of the compound layer on the surface of nitriding layer was mainly γ‘-Fe4N and ε-Fe2~3N. In the experimental range, with the increase of temperature or time, the penetration depth and surface hardness of the material increased, and the wear rate decreased. However, when the temperature was too high or the time was too long, the surface hardness decreased and the wear rate increased. The surface of plasma nitriding material had the best tribological properties at 480 degree and 20 h. The surface hardness was 1147 HV0.2, wear rate was 2.13×10-5 mm3/(N?m), nitriding layer depth was 0.24 mm, compound layer depth was 14.05 μm, friction coefficient was 0.45, and wear state was abrasive wear. Ion nitriding is a surface strengthening method suitable for variable cross-section springs and can form a nitriding layer with a certain thickness and uniform distribution on the surface of materials to significantly improve the surface hardness and wear resistance, and reduce the friction coefficient.