JK chats about her new novel, gives Jeremy a taster from the new book, and talks about the inspiration behind the novels.
She also talks about the impact her books have had on children's literature.
Interviewer Jeremy said: "She talks honestly about her fame, her wealth and the time she even considered breaking her arm to avoid the pressures of writing.
Worth the wait
"As well as dropping some clues about what will happen in the Order of the Phoenix, she raises intriguing new possibilities about Harry's longer term future.
"We've been trying for 18 months to get an interview with JK Rowling - I think it was worth the wait."
We think it probably was! Don't forget to tune in.
And don't miss all the amazing OOTP stuff CBBC Newsround will have in the run-up to OOTP's release and afterwards!