Abstract: Due to its high melting point, high thermal conductivity and strong irradiation resistance, tungsten (W) has been regarded as an important candidate material for plasma facing components of future fusion reactor. However, the void superlattice produced in pure W during irradiation seriously affects its properties. In this paper, the phase-field model of void superlattice formation in pure W during irradiation was improved, and the generation of irradiation point defect with random distribution in space and time was used. The simulation results show that the directional diffusion of interstitial atom and its interaction with vacancy lead to the formation of void superlattice during irradiation. The directional diffusion of interstitial atom along different directions leads to the different types of void lattice. The arrangement of voids in the lattice becomes orderly with the extension of simulation time, and the size of hole becomes basically the same. However, the shape of void is not a standard circle, which is consistent with the experimental results.