AbstractLean alloy (low alloyed) is beneficial for long-term sustainable development of metal materials. Creating a nanocrystalline microstructure is a desirable approach to improve biodegradability and mechanical properties of lean biomedical Mg alloy, but it is nearly impossible to realize. In the present study, the bulk nanocrystalline Mg alloy (average grain size: ~70 nm) was successfully obtained by hot rolling process of a lean Mg-2wt.%Zn (Z2) alloy and both high strength ((223 MPa (YS) and 260 MPa (UTS)) and good corrosion resistance (corrosion rate in vivo: 0.2 mm/year) could be achieved. The microstructure evolution during the rolling process was analyzed and discussed. Several factors including large strain, fine grains, strong basal texture, high temperature and Zn segregation conjointly provided the possibility for the activation of pyramidal slip to produce nanocrystals. This finding could provide a new development direction and field of application for lean biomedical Mg alloys.