I am currently a O-1 visa holder. My "extraordinary ability" in science have been demonstrated to USCIS more 2 years ago when they approved my O-1 visa application. Now it is time for me to apply for U.S. Green Card, and it is logical for me to apply for it in EB1 Extraordinary Ability category. 

My question is that do I need to provide all required documents, including all of the reference letters, to demonstrate my "extraordinary ability" in science again to USCIS to get the approval of Green Card in EB1 Extraordinary Ability category.

For O-1 nonimmigrant visa as aliens of extraordinary ability, the prior approval of your O-1 visa application may be a relevant consideration in USCIS adjudicating the EB1 Extraordinary Ability application, but USCIS is not bound by the fact that you were previously approved the O-1 visa. Because the eligibility as an O-1 visa does not automatically establish eligibility under the EB-1A criteria for extraordinary ability. 

USCIS will consider the O-1 visa application and the EB-1A application separate and independent, and adjudicate on its own merits, under the corresponding statutory and EB-1A regulatory provisions. Previously, USCIS provided explanation as to why the alien is not eligible for EB-1A employment-based immigrant visa, if the alien had previously been approved in an O-1 nonimmigrant visa. Therefore, the alien applicant need to meet its burden to establish eligibility for approval of the EB-1A I-140 petition.