During the past seventy years，the United Nations has promoted the trends of pluralism，equality，and inclusiveness in the postwar international system，and it has contributed to the construction of international law as well as to the setting of global agendas. In many respects，the role of the United Nations is irreplaceable. The new post-2015 development agenda will be one of the future focuses of the UN，and additionally the UN is expected to play an important role in areas like climate change，counter-terrorism，humanitarian assistance，and conflict resolution. However，due to increased tensions between the great powers，it will be difficult for the UN to play a role in some hot-spot issues，such as in Syriaor and Ukraine. The reform of the United Nations and the selection of the next UN secretary-general in 2016 will attract more attention during the seventieth session of the General Assembly. Chinese leaders have clarified China’s new development and security concepts in the UN and have expressed China’s further support and commitment to the UN.