The utility said more towers will be constructed this year at various locations along the route of the line.
Related works including the construction of access tracks have been underway throughout the past year.
Electricity generated from wind farms transmitted by Scottish Hydro’s network crossed 1,000MW for the first time on 14 February 2012.
SSE director of transmission Ian Funnell said the work on the replacement line is important in order to upgrade the grid to accommodate further onshore wind, new offshore wind and emerging marine generation in the north of Scotland.
"The work on Beauly Denny has been progressing well and today marks an important milestone for the project" added Funnell.
Work on the new line is scheduled to be completed in 2014.
