Abstract: Medium manganese steel of high wear resistance, high strength, and high toughness was prepared by using a complex modifier composed of Nb, N, RE, and Si Ca. The mechanical and tribological properties of the steel were investigated. The wear mechanism of the steel characterized by plastic deformation was investigated by means of plastic elasticity calculation and transmission electron microscopic observation. The relation between the wear resistance and yield strength of the modified medium manganese steel was then established. The results show that the wear resistance, strength, and toughness of the modified medium manganese steel are 1.92 times, 1.45 times, and 3.63 times of that of the unmodified medium manganese steel, respectively. The calculated wear rate of the modified steel roughly agrees with the testing result. Thus the increased wear resistance of the modified medium manganese steel is attributed to the considerably increased yield strength and the work for initiation and propagation of cracks.