Under the theme of "20 Years of ASEM: Partnership for the Future through Connectivity", the biennial meeting brings together high-level delegations from 51 ASEM partners - 30 European and 21 Asian countries, and two intergovernmental organizations.
Premier Li Keqiang is scheduled to address the First Plenary Session of the summit on Friday morning.
Li is expected to elaborate China's proposition on ASEM's future development, Asia-Europe cooperation, as well as major international and regional issues, according to Assistant Minister of Foreign Affairs Kong Xuanyou.
Attending the summit are presidents of Bulgaria, Croatia, Cyprus, the Czech Republic, Latvia, Myanmar, South Korea, and Switzerland; and vice-presidents of India and Indonesia.
China and another 22 countries are attending the summit on a head-of-government level, whereas the remaining 16 country attendees are foreign ministers, according to a press release.
"The people and the state of Mongolia have placed paramount importance on the ASEM Summit, which is currently under the global spotlight," said Tsakhiagiin Elbegdorj, President of the Mongolia, the host country.
This year marks the 20th anniversary of ASEM.