Diplomats said it appeared unlikely there would be another vote to try to renew the mandate before it expires on April 30
Liu's visit comes as Washington and its allies urge Beijing to agree on tough new United Nations Security Council sanctions against North Korea after it conducted a fifth nuclear test in September.
North Korea's KCNA news agency said Liu led a Chinese delegation attending the third meeting of the DPRK-China border joint committee. The Democratic People's Republic of Korea is the North's official name.
China is North Korea's main ally but is angered by Pyongyang's nuclear and ballistic missile tests.
China's foreign ministry did not immediately respond to a request for comment.