應該去LV辦一個複印件，然後到Nevada州務卿認證，然後就可以用了。

對於海牙公約成員國（中國去年加入）美國國務院隻管聯邦文書。結婚證是州文書，應該去州務卿那裏辦。

https://travel.state.gov/content/travel/en/records-and-authentications/authenticate-your-document/apostille-requirements.html?

see state and local document section

結婚證書，LV本縣

https://www.clarkcountynv.gov/government/elected_officials/county_clerk/other_services/marriage_certificate_(ordering_marriage_certificates).php

州一級附加說明書（apostille) 

https://www.nvsos.gov/sos/businesses/apostille

然後就可以回國用了。