Pls Help: birth certificate for I-485?

Now I am preparing for filing application for I-485, and I am asked to provide "notary-issued birth certificate"? What does this mean? Which department in China issue the birth certificate? Does it need to be translated into English? Does it need to be verified in the United States? Is there anyone know something about this? Thanks.

BTW., I was born in mainland China. Thanks for your help.