China Embassy Legalization is a phrase widely used by legalization organizations; if you wish to work, get married, or work abroad, some certification is required to recognize your document as China is a non-Hague convention country; this process is called document legalization.
The Chinese Embassy has some specific instructions to acquire its certification.
We remind you that Hong Kong and Macao accepted the Hague Convention in 1997 and 1997, respectively.
So when you travel to one of these cities, all you need is the apostille stamp to use your document.
The embassy does not allow the document to be accompanied by statements from another State that could change its jurisdiction. The rules vary from consulate to consulate, but all require the G1 form “Request for Authentication or Notarization”. This form must be completed and signed by the person or persons working for the company requesting authentication. This person does not have to be the same signatory of the document, but must work for the same company. The signer of the G1 form must also present a copy of their photo ID. The embassy or consulate compares the signatory's signature on the identity card and the form to confirm that they are identical. Even if the ID has expired, the document is rejected. We provide China Document Legalization for all types of documents from the Chinese embassy in Washington DC or from one of its consulates.

For more: https://www.chinaembassy.us/china-embassys