The Executive Yuan has been organized assertively on the basis of "8 ministries and 2 commissions" after the Central Government withdrew to Taiwan in 1949. But, in fact, with the help of the Article 6 of the Organic Law of the Executive Yuan and other special laws, the Executive Yuan has ever installed several ministry or commission-leveled organizations, according to demand of the government. In this paper, we phrased the history of the post-war Taiwan into four periods first, and then analyzed the structural changes of the Executive Yuan in accordance with the change in the role of the government.