Abstract: Based on the asymptotic method for high frequency electromagnetic field coupling to single wire above the ground, an asymptotic method for multiconductor transmission line (TL) is proposed. The proposed method simplifies the solving process of the scattering/reflection parameters required and therefore becomes more efficient than the previous asymptotic method for multiconductor TL. The induced currents along multiconductor TLs with different configuration are calculated using the proposed method, and the results are in good agreements with the simulated results of NEC, a full-wave analysis software. Moreover, the influence of the separation distance between the wires of the rectangular TL and the parallel TL on the induced current is analyzed. Results show that the induced currents along these two TLs change in the rectangular TL and the parallel TL change in different way, as the separation distance between the lines increases. Especially, the induced current along the parallel TL no longer changes while the separation distance increases to more than a wavelength, and is the same as that along the single wire above the perfect conducting ground with the same structure.