Also thought to have been in running for the sought-after role was Neighbours actress Michelle Ang.
The Potter insider who spoke to The Mirror said Katie was "pretty and bright" and that she had a "glittering career ahead of her".
Although she appears in book 3, The Prisoner of Azkaban, it was decided Cho would not actually be in the films until GoF.
Harry finally plucks up the courage to ask Cho to the Yule Ball in GoF. She turns him down because she's seeing Cedric Diggory.
Daniel Radcliffe said way back in 2002 that he was excited about seeing who would be playing his Cho, but said he would not get to help decide who played her.
Katie goes to a private college in Scotland and lives with her dad, two brothers and a younger sister, reports the Mirror.
Her dad was born in Hong Kong, but moved to Edinburgh, where JK lives, years ago.
The family now live in Motherwell, near Glasgow.