The Doctor Who star plays Prince Daemon Targaryen in the new HBO series set 200 years before the events of Game Of Thrones, and admitted that while he hasn't even seen the show himself, he is expecting it to have a style all of its own.
Smith told ComicBook.com: "I think it's really different to the original series, to be honest with you.
"I mean it has to be. The original series was its own thing and it was, it was so brilliant and, and sort of left a mark in a way that it would be impossible to repeat. So, I don't know.
"The truth is I haven't seen any so it's difficult for me. Essentially it's in the same world, it has to take on a slightly different identity. But who knows? I have no idea."
It has been confirmed that the 10-episode series will launch this year with a the first trailer released last year.
The series is set 200 years before the events of Game Of Thrones and is inspired by the George R R Martin book Fire & Blood.
It is set to follow the story of the powerful Targaryen family and a civil war that took place known as the Dance of the Dragons.
Their descendant Daenerys Targaryen was a major character in the main series, with Emilia Clarke in the role.
The new series will star Paddy Considine as Viserys Targaryen, the king of Westeros.
Smith will play his younger brother Daemon Targaryen and Emma D’Arcy will star as Rhaenyra Targaryen, Viserys' daughter by his first wife.
Other cast members include Steve Toussaint, Rhys Ifans and Olivia Cooke.
Smith, 39, played the eleventh Time Lord in Doctor Who between 2010 and 2014.
He admitted despite the immense pressure of starring in the highly anticipated Game Of Thrones spin-off, nothing compared to taking on the role of The Doctor.
He said: "I got the part for that nearly six to seven months before it was announced so I had to keep it a secret for like seven months that I was going to be in it; people going like, 'What are you gonna do next?' I was like, 'I don't know,' but I knew I was going to play the Doctor.
Watch: The first trailer for House Of The Dragon