The coupling characteristics of shielded multi-core cables in high-altitude electromagnetic pulse（HEMP） irradiation environments are investigated through simulation and experiments. Firstly, the coupling characteristics of shielded multi-core cables under different conditions are studied via simulation, revealing the effects of cable wiring methods and parameters on coupling characteristics. A horizontally polarized radiating wave electromagnetic pulse simulator is then constructed for irradiation testing. The results show that an open-circuit shielding layer leads to high voltages coupled onto the core wires, matching the shield voltage, while the grounding shielding layer significantly reduces the coupled voltage on the core wires. Additionally, increases in cable height and length result in higher levels of coupled current. The test results verify the validity of the simulation model and the accuracy of simulation results.