In recent years, volatile corrosion inhibitors (VCIs) have been proposed for self-depositing on the coating surfaces of key structural elements as a secondary measure to mitigate ingress of harmful substances in nuclear facilities. While the integrity of such protective layers and their adherence to the structural surface play a critical role in determining their effectiveness and serviceability, their degradation and damage under irradiation remain poorly understood. To elucidate the underlying damage mechanisms, molecular dynamics simulation is employed to reveal the formation of 6 typical VCI depositions on the steel surface, chemical bond scission and molecular degradation, as well as damage in the VCI protective film upon irradiation at an incident energy of 100 -1000 eV. The results demonstrate that the irradiation energy dictates the damage modes - low energies mainly cause surface group dissociation and slight mass loss, whereas high energies lead to molecular backbone fracture, release of small molecules and hydrocarbon fragments, and damage penetration. The VCI possessing aromatic structures and dense film packing exhibits superior irradiation resistance, showing a nonlinear increase in degradation rate with respect to incident energy. Furthermore, comparative analysis indicates that benzene rings enhance irradiation tolerance through energy dissipation and local stabilization. This study provides fundamental insights into VCI degradation under irradiation and offers guidance for designing high-performance VCIs to enhance the service life of nuclear structural elements.