My dog always eat her after she poo poo.. No matter how we bit her, she don't care, she still eat her POO POO when we didn't notice.

What do you mean no mater how you bit her?

Dogs eat their poo for various reasons, could be hungry, lack of nutrition some commercial brand dog foods don't have the proper nutrients they need, and some dogs will eat their feces if they are fed too much, parasites, boredom, cleaning their mess up, curiosity, he may be anxious or nervous that you will be upset, some dogs just like the taste of it.

You can try sprinkling a little meat tenderizer on her food, which is supposed to make the poop unappealing to them. You can also try crushed pineapple, but I have never had a dog who would eat the pineapple.

Is this the same animal that won't walk on a leash?

How old is she?

This may help you understand your dog's behavior a bit more. Please pay attention to the part about scolding (hitting) can increase the behavior as the animal learns it gets attention from eating its feces:
Douglas Island Veterinary Service - Coprophagia (http://home.gci.net/~divs/behavior/coprophagia.html)

My dog used to eat his fecal matter when he was eating purina (GAG) anyway, after research (and help from people on here) he is now eating evo, and he hasn't ate poop since! I'd recommend getting a better quality food!

A really good way to prevent dogs from eating their poo is to clean up after them immediately.

Poo eating is habit forming. It comes from a bored dog. There is debate about it coming from a dog that has a lack of nutrition in its dialy diet.. Also dogs that want to clean up after themselves.

I have heard that pineapple will help dogs to stop eating their food along with meat tenderizer. There are little pills you can purchase called Deter. From experience, you have to feed A LOT of little pills...

You can also train your dog the leave it command. Any time you see him sniffin poo, tell him to leave it and redirect his attention to maybe a bone or a really yummy treat. This method will take time and patience whereas the other methods are almost instant.