The wear behavior of the MC and NC structured GW63K Mg alloy was studied at the sliding speeds of 0.05 m/s and 0.2 m/s. An adverse correlation between hardness and wear resistance has been confirmed, which AZD1208 related to the different wear mechanisms under different sliding speeds. During the low speed sliding of 0.05 m/s, abrasive wear dominates for both MC and NC GW63K Mg alloy. In the case of MC Mg alloy, wear behavior is mainly performed by ploughing. The NC structured Mg alloy induced by SMAT exhibits a poor wear resistance due to the outstanding effect of fracture arising from the low ductility and toughness. Under the high sliding speed of 0.2 m/s, the wear mechanism is incus transformed into oxidative wear with a low friction coefficient and a small wear mass loss. However, oxide wear debris filling into the worn surface serves as the source of micro-crack, which induces the occurrence of delamination mechanism for NC structured GW63K Mg alloy and results in a worse wear resistance.