He was ambassador of the Republic of China to Nicaragua and Guatemala before serving as foreign minister during the Ma Ying-jeou presidential administration.

Upon graduation, he then went on to serve in the government in several diplomatic capacities, mostly with Central and South American nations.

Ou had planned to retire after turning 65 and applied for permanent residency (‘green card’) in the United States of America.

Ou, however, claimed that he was merely planning for his retirement, for most of his family members live in the US, and applied for a green card out of realistic thinking.

Ou reportedly underwent surgery in August 2021, and was hospitalized before his death on 30 October 2021, aged 81.