The work aims to improve toughness and wear resistance of 45# steel by performing surface strengthening treatment. Three different kinds of treatment were performed to 45# steel substrate in TRD method, which were single-osmosis vanadation, penetration vanadation after first nitriding and nitriding pre-infiltration. Microstructure, phase composition and hardness of the layer were analyzed with scanning electron microscope, X-ray diffractometer and Vickers hardness tester, respectively. Wear resistance of the coating was analyzed with ball-on-disk configuration. After TRD treatment, a uniform and dense layer took shape on the 45# steel, the single vanadium layer was 3.86 μm thick, the penetrated vanadium layer after first nitriding (first nitriding layer) was 6.02 μm thick, and the nitrided layer after first penetrated vanadium (first vanadizing layer) was 8.44 μm thick. Hardness of single-osmosis vanadium was about 1306.6HV, while that of vanadium nitride layer was 1549.2~ 1710.4HV, obviously higher than that of the pre-treatment sample (295HV). The single-permeable vanadium diffusion layer was composed of α-Fe and VC, while the composite layer was composed of VN, α-Fe, Fe3N and Fe2C. There was visible interface between the diffusion layer and the substrate, and there was transition layer as well. Average friction coefficient of single vanadium sample was 0.22, that of first nitriding layer was 0.18, and that of the first vanadizing layer was 0.20, which were all below that of 45# steel substrate (0.29). The VC and VN layers forming after TRD treatment could improve surface hardness and wear resistance of the substrate. Order of element penetration has effects on mechanical properties of the layer. The reciprocating friction experiment shows that the order of wear resistance is as follows: first nitriding layer>first vanadizing layer>single vanadium layer>45# steel substrate.