At present, the research for gas-insulated transmission line(GIL) lacks quantitative analysis of the influencing factors, especially the ventilation speed when pipe gallery is laid, the solar radiation temperature field distribution and the thermal characteristics of open-air arrangement. Therefore, the multi-field coupling analysis method is used to carry out the GIL temperature field distribution based on COMSOL. Its influencing factors are studied. The multi-physics coupling calculation model of electromagnetic field thermal field is established, and the influence of different operating environments on the thermal characteristics of GIL is analyzed. The results show that under the influence of pumping speed and solar radiation, the axisymmetric distribution of GIL temperature field is destroyed and the magnitude and position of shell temperature extremes change. The thermal properties of GIL in different operating environments are different. With the increase of pumping time and pumping speed, the difference between inlet temperature and outlet temperature gradually increases, and finally tends to a stable value; the GIL shell temperature extreme point changes with the change of sunshine direction and intensity. The influence of field distribution can not be ignored. In the case of three-phase vertical arrangement in the GIL pipe gallery, the temperature between the casings has little effect when the casing spacing is left with a suitable heat dissipation distance.