Mao joined the Foreign Service in August 1995 and has served primarily in the Asia Department of the Ministry of Foreign Affairs. She was deputy secretary-general of the Trilateral Cooperation Secretariat in May 2011, and held that office until May 2013, when she was appointed counsellor of the Chinese Embassy in the United States. She was recalled to the original department in November 2015, and was eventually promoted to deputy director in November 2017.
