Based on the density functional theory DFT/BVP86 at 6-311++g(d,p) level, the ground states of ZnO molecule under different external electric fields are optimized. The influence of external electric field ranges from 0 to 008 a.u. on the geometrical parameters, dipole moment, total energy, energy gap., Infrared spectrum and UV-VIS absorption spectrum intensity are studied. The results show that the change of molecular structure is obvious, and it becomes strongly dependent on the field strength. As the electric field changes from 0 to 008 a.u., the bond length of ZnO molecular increases. And the electric dipole moment is proved to be increasing and the total molecular energy is decreasing all the time. The energy gap of EG is found to decrease with the increasing external field. The IR vibration spectrum of ZnO molecule shows an observable red shift. The oscillator strength of UV-Vis absorption spectrum is proved to be repeating the changes of the first increasing and then decreasing. The ultraviolet absorption peak is blue-shifted with the increase of the field intensity.