「入聯」，是2000年政黨輪替之前，國民黨政府執政時期所默默推動的外交政策；因為力道遲緩、能見度低，故成效有限。然而，當陳水扁總統將「入聯」與「公投」相結合時，卻對美、中、台三方造成若干衝擊。 在兩岸的政治格局中，長久以來始終存在著美國勢力的介入；而分析三方的互動過程，各國皆以追求其國家最大利益作為政策產出的準據。因為，「國家利益」被視為是國家生存與國家安全最重要的核心。 儘管，台灣方面所提出的「入聯公投」，已隨著2008年總統選舉的結束，而煙消雲散。然本文試圖藉由台灣所提出的「入聯公投」事件，觀察美、中、台三方所引發的一連串互動，歸納其對於「國家利益」的基本界定與策略調整。希冀利用理論推演與實務觀察的方式，找出美、中、台三方戰略互動的模式與規則，以提供我政府在政策擬定之依據。 “Returning to UN” was the diplomatic policy of KMT before 2000. KMT was conservative, and it was not surprising that there was very limited progress in the promotion of this policy. However, ex president Chen Shui-Bian combined “returning to UN” with “referendum” and resulted in very shocking impact to the United States, China, and Taiwan. The United States of America has always played an important role in the interaction between China and Taiwan, and the main concern of the three countries is their individual national benefit, which is the core of survival and security. Though “Referendum of Joining the United Nation” raised by Taiwan vanished with the ending of presidential election in 2008, this study still tries to discuss the series of interactions between the United States, China, and Taiwan after the referendum, and tries to conclude the definition of “national benefit” and the adjustment of relevant policies. Moreover, with observation and theoretical analysis, models and principles related to how the three nations interact are proposed, which could be reference data for the government of Taiwan in making relevant policies.