Abstract: A large magnetic field is generated in the UHV GIL gallery under short-circuit fault conditions, threatening the normal operation of the monitoring and communication equipment in the gallery. Based on the analysis of GIL short-circuit current conduction and magnetic field coupling process, a spatial magnetic field simulation model of Su-Tong UHV GIL integrated gallery is established in this paper. The calculation results show that the magnetic field at the end of the gallery is the largest (up to 10 mT) and decays rapidly towards the inside of the gallery. Thus, GIL gallery can be divided into port area, attenuation area, and near zero field area. Based on the calculation results, the magnetic field on the surface of the GIL supporting steel structure and the shell conductor of the gallery port area exceeds the immunity test value of 1 s to 3 s short-term power frequency magnetic field specified in standard GB/T 17626.8, so it is suggested that the weak current equipment such as monitoring and communication should be arranged far away from the gallery port area, especially the adjacent location of the shell conductor.