This is an analysis to view foreign policy as an integrated structure of assumptions, objectives, and means. Since American policy during the first Taiwan Strait crisis is the turning point of the U.S.-Republic of China (ROC) relations form the coordination of short-term respective policies to long-term close cooperation based on treaty commitment, special attention is paid to the correlations between US-ROC Mutual Defense Treaty and the fist Taiwan Strait Crisis, the negotiation of the Treaty, the negotiation of the Treaty and the related exchange of notes, and the passing of the Formosa Resolution as well as its influence on the cease-fire in the Taiwan Strait. From U.S. point of view, the Republic of China is indispensable to the island defense chain in the Western Pacific, and Communist China is the spearhead of the expansion of international communism. The struggle between ROC and Communist China in the Taiwan Strait is, therefore a part of the confrontation between the free world led by the United States and the Communist bloc led by the Soviet Union. Accordingly the Eisenhower administration concluded the defense treaty with the Republic of China and passed the Formosa Resolution to leave no doubt of American intention regarding Taiwan, the Pesacdores, Quemoy, and Matsu. Thus the cease fir attained. The Treaty, moreover, not only established the legal basis of US-ROC long-term close cooperation but also strengthened American policy of non-recognition of Communist China as well as that of opposition to communist China’s participation in the United Nations. U.S. policy of containment and isolation toward Communist China thus solidified.