3 Answers

Keep them separated or get a muzzle for her if she does not stop attacking him. They both should be fixed (spayed and neutered). If they are not, she will get aggressive with him if she is not "ready". There has to be a reason she attacked him. Find the reason. Do they get enough exercise? Pitts are high energy. They get bored easily if they do not have enough running around time. Boredom can cause aggression.Take them for walks together.  Get them outside where they can run. Make sure he is not doing anything that aggravates her. If she injured him, he needs to see a vet. 

Colleen

Well, he has been neutered. She has been spayed. Having them walk together and run (supervised) together and play together will build more of a pack mentality. You must be right there to be the "alpha dog". She must know you are in charge, not her. If her aggression continues, have her vet checked. It might be something medical. Something bothering her that can not be seen.

Get both of them neutered if you haven't already done so,there will always be problems unless this is done.

A matter of Urgency get them both done now keep them separated till they are done if you cant muzzle both this will stop the fighting and should keep them both settled good luck i know you love them both but this happens sounds like she could be jelouse or he is showing his dominace with her and she aint putting up with it good luck Hun