Mr. Siew began his civil service career at the Ministry of Foreign Affairs in 1962. He was soon appointed vice consul at the ROC?s Consulate General in Kuala Lumpur and then appointed Consul. He held the position of consul for 3 years. Once home, he became a section chief in the East Asian & Pacific Affairs Department at the Ministry of Foreign Affairs. In 1972 he rose to department director-general. Trade negotiations and market promotion were two areas to which he was particularly dedicated.
As member of the ruling Kuomintang (KMT), Mr. Siew was elected in July 1988 to the KMT Central Committee. In June 1990 a new premier was appointed and the cabinet was reshuffled. Mr. Siew was appointed Minister of Economic Affairs. In November 1992, he helped to secure formal observer status for the ROC in the General Agreement on Tariffs and Trade (now the World Trade Organization.) In August 1997, soon after the National Assembly had completed a revision of the Constitution, the government reorganized the cabinet. President Lee Teng-hui appointed Mr. Siew premier. He took office in September of that year and held the position until May 2000. Mr. Siew has since retired from government office and spends his time as an ordinary citizen devoting his efforts to education and social welfare.