High pressure torsion (HPT) was employed to fabricate nanostructured α-uranium successfully. The evolution of microstructures (grain size and dislocation density) and related mechanical properties (hardness and elastic modulus) varied with strain were quantified and analyzed. The steady-state microstructures and microtextures of the nanostructured α-uranium were characterized by transmission electron microscopy (TEM) and transmission Kikuchi diffraction (TKD) analysis in scanning electron microscopy (SEM), respectively. The grain/subgrain size of the nanostructured α-uranium is below 100 nm, and a weak microtexture with four components is presented. The microstructure evolution of α-uranium during severe plastic deformation (SPD) could be divided into three stages, and it resonates with the variation of creep resistance as a function of strain. On account of the unique crystal structure of α-uranium, the grain refinement limit was discussed and compared with 25 pure metals from a statistical view.