Using B3LYP calculations on the 6-311G ++ (d, p) group, the structural characteristics and dissociation properties of the chloroethane molecule are discussed from the perspective of molecular structure under an external electric field (0~10.28 V·nm^-1). The calculation results show that with the increase of external electric field, the total energy of the molecule increases, the bond length of the C—C single bond decreases, the bond length of the C—Cl bond increases, the dipole moment increases, the size of the energy gap bond increases and then decreases. At different frequencies, the infrared absorption peaks respectively have red shift and blue shift phenomena, and the intensity of the Raman peaks changes. In addition, with the increase of the external electric field, the dissociation energy gradually decreases, and it can be seen that the potential energy barrier almost no longer exists when the external electric field reaches 18.00 V·nm^-1, representing that the degradation of the chloroethane has been achieved.