if i have invitation letter, do i need to provide my bank statement in able to get a tourist visa?

If it's the first time to apply for the Chinese visa, you need to provide bank statement for that. There is no specific requirement for how much you should have in your bank account, but you need to make sure that you have enough travel fees to cover your expenditure in China.

thank you bryson...i have a previous entry permits before in china, does it mean that they don’t need my bank statement anymore?and can I apply or should they will approve if i will apply for multiple entry visa?

If so, the bank statement is not required. It's possible for you to get multiple entry visa if you apply for it. You can have a try.

ok bryson...your response is really a big help to me and gives me an idea regarding my visa application....thank you so much and more power!