Abstract: The structural, elastic and electronic properties of PuO₂ were investigated by means of density functional theory using the full-potential linearized augmented plane wave (FLAPW) method and the local spin density approximation (LSDA) and the generalized gradient approximation (GGA) with on-site Coulomb repulsion U (LSDA/GGA+U) method. The results indicate that the lattice parameters and the bulk modulus of PuO₂ are in good agreement with the experimental data. The U value of 5f in Pu makes the system change from a conductor to an insulator, which is in accord with the experiment. In particular, the localization of 5f weakens and the domain enhances, and there is characteristic of bond formation between Pu and O.