It might also be a good idea to look at the introduction/preface of some qft books you are interested in studying, there authors typically say what they expect students to know, and sometimes where they intend to start from more basic foundations than other authors.
I don't think there is a really general answer to that. You can study QFT from a very pragmatic point of view (“teach me how to calculate these numbers”) or from a rather formal mathematical (physics) point of view, or anything in between. Those will obviously have quite different prerequisite.
Your profile says that you have not finished high school. Do you ask this because you want to know what courses to take when your and undergrad student?
If you ask this because you want to study quantum field theory while you're still in high school, then I think that you're jumping the gun. What is your background in mathematics? What is your background in classical mechanics? What is your background in quantum mechanics? Be specific.