The invention relates to a 66kV-220kV power transmission line composite wire seam electrified adjusting method. The method includes the following steps that first, ground potential personnel on a tower make the front end of a rigid insulating ladder block the position of a wire press-connecting tube and bind the rear end of the rigid insulating ladder to the tower body of the iron tower with an insulating rope; second, equipotential personnel enter a strong electric field; third, a wire clipping device with a tackle is installed in the position away from the wire press-connecting tube for 1.0 m, a lock tackle is installed on working holes of two yoke plates, the insulating rope is threaded into the lock tackle and then threaded into the tackle of the wire clipping device along a wire, and a lock is installed on the lock tackle in the direction opposite to the wire; fourth, the ground potential personnel thread the pulling end of the threaded insulating rope into a tackle of a cross arm head of the iron tower with an insulating rod, and the insulating rope is tensioned at the foot of the tower with a winch so that the tension of the wire can be transferred to the insulating rope; fifth, an equipotential electrician opens a wire adjusting plate to adjust the looseness degree of the wire. The 66kV-220kV power transmission line composite wire seam electrified adjusting method is suitable for 66kV-220kV line equipment in all insulating modes and has high universality.