Victims have long called for Fr Denis Chrysostom Alexander to face trial in Scotland.
He denies the allegations.
Run by Catholic Benedictine monks, Fort Augustus Abbey school in the Highlands closed in 1993.
Allegations of decades of child sexual and physical abuse at the exclusive boarding school were made public in June 2013.
A spokeswoman for the Crown said: “Crown Counsel have instructed proceedings against Denis Alexander.
“Charges are being finalised with a view to seeking his extradition.”
The final decision rests with Australian authorities.