In the Saudi Master Gas System Expansion project, the portal frame of the overhead line of the high-voltage substation was reformed. The safety and stability of the laying of the high-voltage cable was guaranteed through the optimized design of the supporting structure and the production of the high-voltage cable head. Good practical results have been obtained, the construction quality and period have been guaranteed. It provides a guiding and operational statement for the improved technology of portal frame of overhead line in high-voltage substation.