The relationship between different magnetic structures and energies of NpO₂ with a series of U values (3~7 eV) is first calculated by DFT+U method, and then the influence of different point defects in NpO₂ on its architecture and energy properties is studied according to reliable U (4.0 eV). In the calculated results of three different magnetic orders of NpO₂, the structural results of 3 k AFM are in good agreement with the experimental values and obtained a lower energy of formation. Compared with the perfect structure of NpO₂, the energy of formation of single O vacancy system increase by about 0.06 eV, while the energy of formation of the single Np vacancy system increase by 1.4 eV. In addition, we also study the changes in the volume and energy of the system as O and Np vacancies increase.