In addition to the pylons, eight miles (nearly 13km) of cables would be buried underground in the Meifod valley.
National Grid has also identified a preferred "secluded" site for a substation, on the Tir Gwynt wind farm.
Montgomeryshire's Conservative MP Glyn Davies said the scale of the entire project was "completely outrageous".
The wind farm plans have sparked opposition from campaign groups, while a public inquiry is already under way.
National Grid owns and manages the networks that connect people to their energy.
It says a new "T-pylon" - which is about 15m (nearly 50ft) shorter than conventional pylons - could be used along the power cable route, which will be 33 miles (53km) long.
It says it has developed a draft route to keep away from villages and will use "hills and trees as a natural backdrop to help keep any visual impact to a minimum".
About a quarter of the route would be underground.
Jeremy Lee, National Grid's Mid Wales Connection project manager, said: "We recognise the rich cultural significance of the Meifod Valley, which includes Mathrafal and Glyndwr's Way, and understand the potential impact a 400 kV steel lattice overhead line could have on the valley - something people told us was very important to them.
"We think putting this section of the connection underground is the best way to manage these effects and means this area can be largely kept to how it looks today."
Mr Lee said the preferred Cefn Coch substation site was within land that formed the Tir Gwynt wind farm.
"We looked at several sites for the substation and we have selected one which we think best balances all of the factors we must consider," he added.
"We think it offers strong opportunities to reduce visual impact and puts the substation away from villages and caravan parks in the area."
National Grid says it will continue to assess the potential impact of its plans, and wants to hear the views of local people.
It plans to hold events as part of a consultation and says more information is available on its website.
For the past two years, Montgomeryshire Against Pylons has campaigned against expanding the energy infrastructure in mid Wales, as well as possibly hundreds of new wind turbines.
A public inquiry is under way to determine whether those planned wind farms should be allowed.
Montgomeryshire MP Glyn Davies said: "The scale of the mid Wales connection is just completely outrageous as far as the impact on mid Wales is concerned.
"The whole line is making its way through very beautiful countryside and I think they (National Grid) really have to underground the whole line," he told BBC Radio Wales.
The plans in Powys are being revealed two days after people at a public meeting in Carmarthenshire voted against using pylons to connect wind farms to the National Grid.
The county council and others want the lines from existing and planned turbines in Brechfa to be buried.
Western Power Distribution (WPD) said wood pole overhead lines were preferred for its connection plans but it may consult later on burying them.
Richard Bonfield, spokesman for an alliance of 21 groups against wind farms in the area, told BBC Radio Wales: "Our position is that we're totally opposed to wind farms and if there are no wind farms, National Grid substation and pylon route will not be required."
He said burying part of the route was "good news for the people of the Vyrnwy valley," but added he was "really depressed for the people in Shropshire who will still have these pylons".
Shadow Minister for Environment Russell George AM criticised what he said was a  "deafening silence" about the project from the first minister.
"He has betrayed the people of mid Wales and continues to sit back as plans move ahead to blight our landscape despite the wishes of communities," he said.
"The connection project is just part of a larger energy scheme which will industrialise this region."
The Welsh government said it would be looking at National Grid's  proposals closely as more detail became available.
"As consultees, we have consistently made a case for undergrounding cables where possible and welcome the confirmation of significant undergrounding at the Vyrnwy Valley," said a spokesperson.
"However,  major energy infrastructure is not devolved to the Welsh government despite our continued representations to the UK Government that we should be responsible for decisions affecting Welsh communities.
"We will continue to engage with the National Grid to mitigate the impact of new transmission lines."
National Grid has revealed plans to use 25 miles (40km) of pylons to connect to controversial planned wind farms in Powys.