Mithali Raj said she was an avid reader and it calmed "jitters" before her big moment.
Her performance helped India beat England by 35 runs during the tournament's opening day in Derby, and she also broke a world record.
She has been nicknamed "Captain Cool" by fans.
In a post-game interview, she said the book was by 13th-century Persian poet Rumi.
She borrowed it from a coach as she was not allowed to bring her normal electronic e-reader with her.