Using density functional theory at B3LYP/6-311+G(d, p) level, the spectral characteristics and dissociation characteristics of (-0.05~0.05 a.u.) monofluorodichloroethane molecules under different applied electric fields are studied. It includes the ground state structure, total energy, dipole moment, highest occupied orbital energy level, lowest vacant orbital energy level, energy gap, infrared spectrum, Raman spectrum, UV-visible absorption spectrum and potential energy curve of between C and Cl bond under electric field. In the y-axis direction, with the increase of negative electric field, the distance between C atom and Cl nucleus increases, the highest occupied orbital energy level decreases, the total energy of the system, the lowest unoccupied orbital energy level and the energy gap increase first and then decrease, and the dipole moment decreases first and then increases. The applied electric field can affect the absorption intensity and absorption peak frequency of the infrared spectrum, Raman spectrum and UV-visible light absorption spectrum of monofluorodichloroethane. The infrared spectrum, Raman spectrum and UV-visible light absorption spectrum appear red shift or blue shift with the change of electric field. The barrier between C and Cl atoms gradually decreases with the increase of negative electric field and reaches -0.05 a.u. When C atom breaks with one of the Cl atoms, when a C—Cl bond in the molecule breaks, the applied strength is -0.04 a.u. When the electric field of, another C—Cl bond is broken, and the molecule is gradually dissociated under the electric field. The research results improve the theoretical data of the influence of external electric field on mono-fluorodichloroethane molecules.