In recent years, in order to reduce shielding failure of tension tower in 500 kV compact transmission line, jumper structure with bypass shielding wires is mounted on the tension tower. This leads to several single-phase grounding faults caused by the falling of bypass shielding wire onto the conductors. The faults reasons were analyzed from the aspects of the mechanical model and T-connection fittings. Several measures were proposed to improve operating security of the line, such as applying performed helical T-connection fittings, optimizing the installing position, length, sag of bypass shielding wire, and so on.