從1960至1970年代，歐洲國家皆遭受過恐怖攻擊，但當時只是將其視為各國內政問題。不過，自冷戰結束後，各國所必須面對的安全威脅變得更為廣泛，而恐怖主義也為其中一項。受到九一一事件的影響，歐盟開始制定相關反恐政策及措施，予以因應恐怖主義的發展。爾後，發生2004年馬德里爆炸案與2005年倫敦爆炸案，歐盟便積極研擬反恐政策及戰略，並且與美國簽署合作決定，藉此打擊恐怖主義。雙方如何透過這些政策、戰略、及合作決定相互增強合作，是值得探討之處。 本文採取新自由制度主義為研究方法，藉此分析及探討歐盟與美國在歐洲地區的反恐合作情況。至於本文的研究內容則分為三個部份：首先，分別探討歐盟與美國在九一一事件前後的反恐政策及戰略發展，以及雙方如何透過各項合作決定來強化合作；其次，針對促成歐盟與美國合作的因素進行分析，並且說明彼此在各國際政府間組織執行反恐合作的情況；最後，則是對歐盟與美國的合作成效提出評估，以及論述未來雙方合作的展望。 本文研究結果則了解到，歐盟與美國在反恐合作的過程中，難免會產生衝突。就整體情況而言，雖然雙方的合作無法完全消滅恐怖主義，但仍是可以抑制恐怖主義的發展，並且竭力為人類帶來和平及安全的生活。畢竟，打擊恐怖主義不是一件簡單的事情。 Although European countries had been attacked by terrorists from 1960 to 1970, they still treated it as home affairs. After the cold war, all countries have to face a more complex security environment, also include the spread of terrorism. European Union (EU) began to establish anti-terrorism policies and initiatives after 9/11 attack in order to restrain the development of terrorism. Subsequently, there were terrorist bombings in Madrid and London. EU not only establishes counter-terrorism policies and strategies with members, but also signs cooperation agreements with United States (U.S.). It will be an important view for how do they strength the mutual cooperation through these ways. This thesis is used “neo-liberalism” as research approach to analyze and discuss the counter-terrorism cooperation between EU and U.S. in Europe. This thesis has 9 chapters, and the structure is divided into 3 parts: first, it will not only analyze the development of counter-terrorism policies and strategies of EU and U.S. separately, but also discuss how they enhance cooperation through the agreements that they’ve signed. Second, it will analyze what kinds of factors promote their cooperation, and talk about how they work hard to against terrorism in intergovernmental organizations. At the end, it will not only evaluate the cooperation efficiency between EU and U.S., also estimate point of views of their future. This thesis concludes that the cooperation process between EU and U.S. would made disagreement or even conflict. Their cooperation may not eliminate the terrorism, but sill can restrain it and bring the peace and security as possible as they can. Fighting terrorism is not a piece of cake, after all.