Effect of heat-treatment on the microstructure and recrystallization behavior of pure Zr was studied. The specimens were prepared under the various annealing temperatures from $400^{circ}C$ to $800^{circ}C$ and times from 300 to 5000 minutes after vacuum arc remelting. The recrystallization behavior was observed by a polarized optical microscope, TEM and micro-vickers hardness tester. With increasing the annealing time, the temperature region of hardness drop moved to the lower temperature region due to the recovery and recrystallization behaviors at the lower temperature. The recrystallization of cold-worked pure Zr was completed between 450 and $600^{circ}C$. The size of recrystallized grain increased at $700^{circ}C$ for 600min. Activation energy(Q) of pure Zr measured by the time for constant fraction technique was 78 KJ/mol.