Copy of the passport photo page for both parents. All the documents must be notarized, certified and authenticated . The seals that are affixed starting from a local notary on up to the Chinese consulate are what validate your documents. Since this guarantees that your documents were properly certified at each level, then the Chinese government can have confidence that the original documents are authentic. This varies depending on what agency you are using.
Some agencies provide almost all of the authentication steps as part of their services.
Others will charge you less and require that you do the authentication steps yourself. We hope to have more detailed directions on authentication of documents available soon.