What is process for Authentification of document in Chinese embassy?

If your document has been authenticated by the relevant state government, you can get it authenticated by Chinese consulate in NY now.
You are required to submit the following materials to the Consulate General:

1) Original documents to be authenticated;

2) One photocopy of the complete documents to be authenticated. Photocopy includes the page authenticated by the Secretary of State, the page notarized by a Notary Public and the original document.

3) One regibly and completely filled out Application Form for Authentication or Notarization(G-1).

4) In cases of commercial authentication, a copy of the company's license and good standing certificate of the company are also required.

And the application can generally be picked up on the fourth working day from the date of submitting.