Pure Cu of 99.99 wt.% purity has been processed at room temperature by equal channel angular extrusion (ECAE), the evolution on the microstructural was characterized by the use of, transmission electron microscopy (TEM) and X-ray diffraction.Starting with a grain size of 110 μm, severe plastic deformation has been introduced to the material while maintaining the sample dimensions unchanged through the processes of ECAE. Besides the temperature effect on the microstructural and microhardness evolution are studied. With increasing annealing temperature, the microstructure becomes more homogeneous while the microhardness decrease dramatically.