重商主義時期“獎勵出口重課進口”的對外貿政策，及產業革命後生產力的擴張，使世界範圍內的傾銷大規模形成；二十世紀七○年代以來，「傾銷」已普遍存在於國際貿易之中，而對於「反傾銷」立法和實踐亦進展迅速，從關稅暨貿易總協定成立以來，對於「反傾銷」的立法、修訂一直是談判內容的主要議題。 本文的目的在探討在產品不完全替代下，面對國外持續性傾銷時，若廠商分別從事Cournot數量及Bertrand價格競爭時，如何課徴反傾銷稅？結果發現若廠商進行數量競爭時則：當本國與外國傾銷品相互替代率相同及本國產品對國外傾銷品之替代率大於國外傾銷品對本國產品之替代率時，本國政府可在社會福利最大化下制定反傾銷稅率。若進行價格競爭時則：本國政府無法依社會福利最大之反傾銷稅率制定反傾銷稅率。 / The mercantilist emphasis on expanding exports while restricting imports, coupled with the expansion of productivity seen following the industrial revolution, led to the proliferation of dumping trade practices around the world. “Dumping” has been a formally-recognized and widespread phenomenon in global trade since the 1970s. Against this, national governments have also been quick to implement countervailing laws and legislation. Anti-dumping legislation has been at the fore of international trade discussions since the General Agreement on Trade and Tariffs (GATT) was established. This paper addresses the issue of how countervailing duties may be most effectively assessed in situations where a national product that is not completely substitutable by import competitors suffers sustained competition from imports dumped on the market. To achieve this objective, our research examines the effects on competition that result from the manufacturer of the national product adopting, respectively, Cournot volume and Bertrand pricing strategies. The result shows that, when a volume strategy is adopted, home government imposition of countervailing duties will be able to maximize social benefit when either domestic and imported (dumped) products share a similar substitutability ratio or the substitutability ratio of the domestic product is greater than that of the imported competition. When a pricing strategy is adopted, the government is, conversely, not in a position to impose a countervailing duty that will maximize social benefit.