Ange is reportedly "furious" with Jane Pitt after she purchased the six-year-old a series of feminine outfits and babyish costumes.
"It's well documented that Shiloh likes to dress like a boy," a source told the UKEvening Standard.
"But Jane still insists on buying her fairy costumes and princess dresses, which Angelina finds very disrespectful."
The actress was said to be appalled with Jane after she wrote a "homophobic" letter to a US newspaper urging Americans to vote against gay marriage just a couple of weeks ago.
Both Brad and Ange are ardent gay right supporters, once claiming they wouldn't get hitched until same-sex marriage was legalised in the US.
Shiloh is renowned for preferring boyish clothes and haircuts, with a magazine once suggesting the six-year-old was a cross-dresser.