The analysis model of electrothermal coupling is established in this paper, focusing on the spring contact finger of a 550 kV GIL. The contact resistance between the spring contact finger and the conductor is calculated through static structural analysis, while the contact temperature rise is determined based on heat transfer mechanisms. This enables simulation of electric heating characteristics under various contact parameters. The results demonstrate that at rated current, the temperature rise of the spring contact finger decreases linearly with an increase in spring wire diameter, whereas it exhibits nonlinear changes with variations in middle diameter of the spring. Excessive or insufficient values lead to increased temperature rise in the contact finger, while an increase in number of springs results in decreased temperature rise. The research presented herein provides valuable insights for structural optimization and service life evaluation of GIL spring contacts.