In order to grasp the circular current characteristics of gas insulated transmission line（GIL） pipe corridor grounding system and the influencing factors of circulation characteristics

theoretical simulation research was carried out for GIL pipe corridor grounding system. The 500 kV GIL grounding system and the shell circular current model were established

and the parameters of self-impedance and phase-phase mutual inductance were analyzed. The results show that the shell circular current value of GIL is about 75% of conductor current. The reliability of calculation results was verified by comparing the decoupling model calculation of ATP-EMTP program with the decoupling model calculation of MATLAB program. And then

the shell potential distribution rule along the GIL corridor was studied. The calculation results show that the shell potential present a U-type distribution

the maximum touch potential difference inside the GIL pipe corridor meet the requirements of the regulations. At last

short circuit connection bar was studied

which shows that the bars can reduce the ground current at the end of the shell significantly. As the number of short circuit connection bar increases

the grounding current at the end of the shell and the shell potential will decrease gradually. The short circuit connection bar can be installed on the aluminum alloy shell at every 80 m.