Abstract: To address the issues of complex electromagnetic environment and difficulty in ensuring electrical stability and safety of ultra-high voltage GIS equipment under compact interval layout, the finite-difference time-domain method can be adopted to conduct transient electromagnetic field simulation analysis. A current source parameter optimization strategy is proposed, with a focus on adjusting the current source position, current direction, and excitation form to optimize the electromagnetic field distribution. The layout of the current source has a significant impact on the concentrated area of the electric field intensity and the magnetic field coupling effect. Reasonable optimization can effectively weaken the electric field spikes and magnetic coupling interference. The results show that edge-arranged current sources, the adoption of staggered or symmetrical excitation directions, and the selection of gentle waveform excitation can effectively improve the electromagnetic environment, reduce the risk of local breakdown and interference, and provide simulation support for the miniaturization and safety design of GIS.