The career path to principal traditionally started in the classroom but, in a major shift, the Catholic education system in Sydney's west says their new school leaders may not be teachers but managers from the private sector.

The Catholic Education Diocese of Parramatta, which runs 56 primary and 22 secondary schools, is building a new school on a greenfield site in Marsden Park, which will be vastly different from existing schools, starting with the principal.

The executive director of schools, Greg Whitby, said the principal of its newest school would not necessarily be a career teacher, but rather someone who was a "bit of an entrepreneur" who will "make connections and manage relationships".

"We are not talking about someone like the CFO of BHP, but it could be someone from the tertiary sector, private education providers, the coaching industry," Mr Whitby said.