The organisation said there were some outstanding issues for which it was seeking amendments of the proposal.
In particular, it wishes to see alternative route options considered in greater detail where the route crosses the Cairngorms National Park and the Ochils, near the
Wallace Monument.
John Thomson, SNH director, said: “This development is seen as the key to unlocking the environmental and economic benefits of renewable energy production in areas
which hold some of the best resources in Europe.
“It will also inevitably impact upon areas valued highly for their wildlife, habitats, and landscapes, and for the outdoor recreation opportunities that they offer.”
He added: “The development will lead to some unavoidable adverse impacts. Our role is to ensure these are minimised as much as possible.
“We will need further information to be supplied and the acceptance of planning conditions, as well as more detailed talks with the developer in relation to landscape
and visual impacts.”
Scottish Natural Heritage has said it is not opposed in principle to plans to build a 137-mile power transmission line of huge pylons from the Highlands.
The 400kV line from Beauly, near Inverness, to Denny, near Falkirk, was the “most extensive development” on which the body had ever taken a view.
It did say it would prefer alternative routes for some parts of the line.
Plans were submitted to the Scottish Executive last year by Scottish and Southern Energy and ScottishPower.