Microstructural evolution of the zirconium alloy deformed at a strain rate of about 1000 s-1 was investigated by means of the experimental design.Four different strain levels the zirconium alloy subjected to dynamic compression were designed by several times impacting at almost same strain rate.Under different strain levels, the stress-strain curves presented the dominant strain hardening behavior, and almost no thermal softening phenomenon was detected.The indexed grain boundary maps show that abundant low angle boundaries at different strain levels were observed in the deformed microstructure, and its quantity and density increased dramatically with the strain increasing.Besides low angle boundaries and high angle boundaries observed in grain boundary maps, the twin boundaries including the tensile twins {10-1 2}, {11-2 1} and compressive twins {11-2 2} were distinguished at different strain levels, and most twin boundaries were indexed as {10-1 2} twins.With the stain increasing, the twin boundary density in the deformed microstructure increased indistinctively.Based on the characterization of the deformed microstructure at the different strain levels, the deformation and evolution process of the zirconium alloy subjected to dynamic loading were proposed.Microhardness measurements show that the microhardness values in the impacted specimens increased gradually as the strain increasing, which should be associated with the strain hardening caused by the dislocation block.