Pauline Hanson said she'd "kick" the nine-year-old girl "up the backside" for her actions.Credit:AAP
She said she believes the lyrics of the anthem marginalise Indigenous people.
"The reason why I don't sing it or stand is because Advance Australia Fair means advance White Australia,"she told News Corp.
"When it says'we are young'it completely ignores the fact that Indigenous culture was here for over 50,000 years before colonisation."
Harper has the support of her"proud"dad Mark,an Associate Professor at the School of Psychology at the University of Queensland.
"She's shown incredible bravery in wanting to stick to what she believes in and to make a stance for what she believes is right",he told ABC radio on Wednesday.
But the stance has outraged conservative commentators and politicians including Pauline Hanson,who posted a video on Facebook calling for Harper to be kicked out of school.