Abstract: With the technological innovation of helicopters and the increasing prominence of strong electromagnetic pulse interference, it is very easy to cause the failure or paralysis of helicopter on-board electronic equipment, which seriously threatens the helicopter′s survivability and combat performance. This paper establishes an electromagnetic simulation model of helicopter and its internal cable system, and analyses the electric field coupling response at typical position under the electromagnetic pulse radiation and the current coupling effect of the helicopter′s internal cable based on the time-domain finite-integral method of CST electromagnetic simulation software. The simulation results show that the portholes and aperture structures have an important influence on the coupled field strength inside the helicopter: the closer the shielding defects are, the higher the internal electric field strength is; meanwhile, the resonance frequency point of the cavity also enhances the coupled field strength. For cables, the closer the shielding defects are, the higher the peak value of the induced coupling current. Coaxial cables with shielding layers have better electromagnetic protection performance than unshielded single-core cables, resulting in a smaller induced current. Additionally, all the cables are affected by the resonance frequency point. This study has some practical engineering significance for the strong electromagnetic protection of helicopter electronic equipment.