My green card has expired on may, I want to apply for citizenship now. I had have my green card for over 6 years or more. Question: do I need to renew my green card in order to apply for naturalization??

As far as I know you cannot apply for citizenship with expired green card which means you would need to renew it prior to application.

USCIS recommends applying for a new green card if your current card is expired or will expire in the next 6 months. If you apply for citizenship more than 6 months before your green card expires, you probably will not have to renew your green card

You will have to apply for a new green card.