A density functional method DFT/B3LYP with SDD basis for Pu and 6-311+G* basis for O is used to study HOMO energy level, LUMO energy level, energy gap, and harmonic frequency of PuO ground state molecule under different inner radiation fields ranging from -0.005 to 0.005 a.u.. The results show that the magnitude and the direction of the electric field have important effects on these characteristics of PuO molecule. The HOMO energy level is found to decrease, but the LUMO energy level, energy gap and Fermi energy level are found to increase with the increase of electric field. The electron which occupies orbital is difficult to stimulate to empty orbital and transform into excited state. The PuO molecule is more stable in inner radiation field, and it can prevent O2, H2 and so on from proliferating to superficial inner layer and corroding the plutonium surface, which contributes to the plutonium corrosion prevention in inner radiation field.