Molecular dynamic simulations were conducted to simulate the collision cascades in HCP zirconium induced by self-recoils in 300 K with primary knock-on atom (PKA) energies setting from 10 keV to 50 keV. Three point defects identification methods, including off-site atoms judgment, SIAs(self-interstitial atom, SIA) determination and WS cell segmentation were used to analyze simulation results. Comparing with the difference of defects evolution, defects statistical fluctuation and robustness of the identification methods, the approach based on the principle of Wigner-Seitz (WS) cell segmentation is considered to be more appropriate in point defects analysis. In addition, the basic diffusion feature of SIA was studied, and the results showed that it is more inclined to a 2D diffusion.