The best-selling novel Streep's new comedy is based on was written by Wintour's former assistant, Lauren Weisberger.
Miranda, the influential, but impossibly demanding fashion editor depicted in the book, is widely believed to be inspired by Wintour, although Weisberger denies this.
"I know the book was based on an assistant's eye-view of Anna Wintour, but it didn't interest me to do a documentary on Anna Wintour," Streep said.
The Oscar-winning actress said she knew very little about Wintour before she met her at a benefit screening of the film.
"It's much more fun for me to make the uber-boss out of my own pastiche of experience," Streep said.
Revealing she didn't know enough powerful women on whom she could model her performance, Streep said she looked to the "male end of the species" for inspiration.