How can I get a visa from Chinese ambassy in Korea!

Your ARC should be valid for more than 6 months in Korea. If yes, you can apply through a travel agency which was appointed by Chinese embassy or consulate. Generally, you are required to provide passport, application form both V2011A and V2011B, a passport photo. You can contact an agency for the lastest requirements anyway. For HK, you need a separate visa but you can apply at the same time from Chinese embassy or consulate.