Abstract: In order to minimize the lightning electromagnetic pulse hazard to electronic equipment installed on stayed-cable bridges, it is necessary to study the lightning-induced magnetic field on the bridges.The"equivalent electrical-circuit method"for the lightning electromagnetic pulse analysis of buildings is applied to the study of lightning-induced magnetic field of stayed-cable bridges.Especially, the stayed-cables of the bridge are transferred as cascade polylines to make the internal metallic structure of the bridge into an equivalent electrical-circuit network.Finally, take the Taizhouwan Bridge under construction for example, the distribution of lightning-induced magnetic field on the bridge is calculated and analyzed with the method proposed in this paper.Then the advice for the protection of sensitive electronic equipment against lightning-induced magnetic field is provided.