Is the copy of invitation or we must bring the original to get china visa?

If you are going to apply for a Tourist visa, then the requirements include:
1) Valid passport(six months or above validity) with at least one blank page for visa;
2) Neatly completed visa application form with one recent photo on it;
3) For first-time-application of Chinese visa, return tickets, hotel reservation or other documents related to the application should be presented upon the request of the consular officer.

If you are going to apply for a Business visa, the requirements also include an "Invitation Letter of Duly Authorized Unit" or "Confirmation Letter of Invitation" from an authorized Chinese institution rather than the company is required. And the original one will be better.