The ground state structure, bond length, total energy, dipole moment, charge distribution, energy gap, infrared spectrum and potential energy surface of cesium bromide(CsBr) molecule under the action of external electric field(-0.015-0.035 a.u.) are studied by using Semi-empirical/PM6 method. The results show that the molecular structure of CsBr changes significantly under the action of an external electric field. With the increase of the external electric field in Cs-Br bond direction, the molecular bond length, electric dipole moment, electric charge population and energy gap gradually decrease, while the total energy gradually increases, and the strongest peak of the molecular infrared spectrum appears blue shift. On the other hand, with the increase of the applied negative electric field, the molecular potential energy surface decreases, and the potential barrier decreases gradually and finally disappears. It is also found that Cs-Br bond of CsBr molecules will be broken under an external electric field with an intensity of-0.015 a.u., leading to the dissociation of CsBr molecules, which provides a theoretical basis for the protection of the atmosphere.