越南擁有 8,000萬人口，是東南亞舉足輕重的國家，其外交政策的發展，是現實主義外交的最佳典範。本文擬從越南自 1975年全國統一到 21世紀初全面走向改革開放為止，以現實主義的「權力平衡」觀點評估其發展。本文首先介紹「權力平衡」概念，再簡述越南外交的各個階段，再以「權力平衡」概念予以檢討，解釋越南外交成功的策略及未來可能的發展。本文發現，冷戰時期，越南借力打力，以「權力平衡」為策略，將自身作為「權力平衡」的支點，拉攏大國對抗另一大國，以獲取支持抗拒外來干預打贏戰爭，並得以在柬埔寨和寮國取得支配地位；其間越南大致上均能維護其自主性，並未完全受制於某一大國，只有在統一之後因美國壓力，中國又和美國改善關係，這時越南採取了冷戰時期第三世界國家「非楊則墨」的慣用模式，導向蘇聯以求制衡美國的封鎖和中國的進攻，本質上仍是「權力平衡」的思維。冷戰結束之後，大國間的對抗緩和下來，越南這時就不惜在外交上做出讓步，積極參與區域組織，以實際作為配合和支持區域內的「權力平衡」，藉機發展經濟、擴大對外貿易，吸引外來投資，開採南海資源，都有顯著的成效。

This article seeks to analyze Vietnam’s diplomatic policy through the conception of “balance of power” in realism. The argument of the article is the Vietnam’s diplomatic situation has remained flexible under the perspective of “balance of power.”. Since the 1950s to 1990s, in order to receive external assistance against its major threat, Vietnam used the “balance of power” strategy, to cooperate with one power against another power, successfully won two wars and unified the country. During the Vietnam War (1959-75), North Vietnam balanced relations with its major allies: the Soviet Union and the People’s Republic of China against France and the United States. In 1978, Vietnam invaded Cambodia; it established even closer ties with the Soviet Union to destroy the Cambodia’s Khmer Rouge regime and against China’s invasion. Following the Cold War, there were fundamental changes in the global security system. Vietnam was aware of the transformation of balance of power in the Southeast Asia. Therefore, it changed its diplomatic strategies, withdrew its forces from Cambodia, rejoin the international community for its national interests. the Hanoi regime actively integrated itself into the international and regional organizations such as WTO and ASEAN and improved the relationship with the other countries to maintain and enhance the“balance of power” situation in the Southeast Asia. However, Vietnam still seeks to ally the other powers, the US, Japan and India, to balance the potential pressure from China.