Born in Chiayi City in the then Japanese colony of Taiwan, Siew graduated from the Department of Diplomacy at National Chengchi University in 1961, and received a master's degree from the Graduate Institute of International Law and Diplomacy at National Chengchi University in 1965.
Born in Chiayi City in the then Japanese colony of Taiwan on 3 January 1939, Siew graduated from Chiayi High School in 1957. He subsequently received his master's degree from the Graduate Institute of International Law and Diplomacy from NCCU in 1965.