Abstract: In order to ensure that the "three-span" conductor tension series does not fall off at the connecting tower,the design concept of "Double triple hanging point" is adopted . Under normal working conditions, only the connecting tower metal string is subjected to force, thus realizing the "Double single hanging point" for the conductor tension series, to ensure the force balance of the two composite insulators under normal operating conditions.The two tower backup strings are designed as "Soft connection", which does not bear force under normal operating conditions, and only bear force after the metal string are broken, realizing two tower backup strings and double hanging point of double insulator. After trial application on the internet, the effect is good.