Well when I was born my dad split because he wasn't ready to be a dad, now after 13 years of me and my sister living with my mom she lost her job. We lost our house from not being able to pay bills. My sister stayed with my mom while I went to go live with my dad and his wife. My dad is pretty wealthy he owns a small business etc, he was money. My step mom has always been nice before I moved in all of the sudden she changed. She tell my dad how to punish me for my grades,etc. I wish I could explain how she is but I feel she does not want me here and is jelous that my dad cares more about me than her and she is not the baby of the house anymore.
A few days ago I got my report card, I did not make what my dad expected so I am grounded. The deal was until the next progress report which is 3 weeks, But all the sudden she is outraged and throws a fit and my dad changes my grounding until next report card in 9 weeks.
My step mom comes in my room randomly and nags about everything I do and I hate it, "Brandon do this,Brandon do that.IF you were my kid your butt would be black and blue,your so disrespectful." She never has anything positive to say about me, she is always putting me down and talking behind my back to my dad trying to control the house.
Every time we get in a fuss she runs off to her moms and talks about how wild and out of control I am behind my back. She also tries to block my REAL mom out of my life. Every time my mom calls she does not answer the phone or is always real smart with her. My mom wants to come and kick her but I do not think that would solve anything.

What do you guy's think?

Tell your dad how you feel and your at least 13 so at the most you have is 5 years of childhood left and then you'll be out, so keep that in your head and don't think about your stepmom, just know that you'll never have to talk to her again in 5 years, trust me, it works

WOW.

You need to make sure you bring this topic up with your dad in a way that makes it very clear you are not asking him to choose between you and his wife. If you make this appear to him as an ultimatum, he will most definitely choose against your side. Don't bring this up as "she's doing this this and this!" As much as you need to vent and tell your dad all about how horrible she is, keep accusations (no matter how true) out of the conversation.

Tell your dad that you feel like you and your stepmom do not get along/have the same expectations of you, and you want his help to fix things. Have this conversation in private between the two of you. Make it clear you are asking for help and advice, not ratting out her bad behavior, and if he's a sensible man and you have avoided demonizing her, he will work with you.

About the report card? Your father set a punishment. You are his child to punish. It is disrespectful of her to undermine his authority as a father by implying he is doing a horrible job and "correcting" him by punishing you further. By the way, I agree that waiting only until the next progress report is very reasonable; if you can improve your grades by then, what is the point in continuing to punish you?

If you haven't already, you can always Google for articles on stepfamily relations. Maybe you will find some helpful advice there. You might even want to print an article that really touches the subject and show it to your father, or your stepmom (either as a conversation starter, or hide it under her pillow anonymously if you don't know how to approach her facetoface.)

In the meantime, examine your own behavior and make sure you are doing absolutely everything within reason on your part to be respectful of her, no matter how frustrated she gets you. Please don't take that bit of advice personally: but think about it. You have been frustrated living with this woman for quite a while now. Could there be a cycle of hostile behaviors that have developed? Work on your grades. Never talk back-- in fact, check your tone of voice when you answer her especially if you are frustrated at the moment, and apologize and correct yourself immediately after ("I'm sorry, I'm tired/distracted/frustrated right now. I didn't mean to sound angry when I said that."). Try to get things done the first time she asks you. Remember that she was there first, and as your stepmother she inherently deserves a certain level of respect (whether she otherwise deserves it or not).

I'm now seeing how long-winded my post is... Sorry about that :-P Hope I was able to help some.