一、最惠國待遇原則的含義以及特征
最惠國待遇（Most Favored Nation Treatment，MFN）是世界貿易組織多邊貿易製度中最重要的基本原則和義務，是多邊貿易製度的基石。世界貿易組織法律製度之所以成為多邊貿易製度，最重要的依據就是其最惠國待遇。根據世界貿易組織的規定，對最惠國待遇原則的修改，必須經全體成員同意才有效。世界貿易組織的《關稅與貿易總協定》第1條、《服務貿易總協定》第2條第1款和《與貿易有關的知識產權協定》第4條中，都有關於最惠國待遇的基本規定。在不同的協議中，最惠國待遇義務的含義並不完全相同，各有其嚴格的適用條件和範圍。
（一）最惠國待遇原則的含義
最惠國待遇指一成員方將在貨物貿易、服務貿易和知識產權領域給予任何其他國家或地區（無論是否是世界貿易組織成員）的優惠待遇，應立即和無條件地給予其他各成員方。
在貨物貿易領域，依《關稅與貿易總協定》第1條第1款規定：With respect to customs duties and charges of any kind imposed on or in connection with importation or exportation or imposed on the international transfer of payments for imports or exports, and with respect to the method of levying such duties and charges, and with respect to all rules and formalities in connection with importation and exportation, and with respect to all matters referred to in paragraphs 2 and 4 of Article Ⅲ, any advantage, favour, privilege or immunity granted by any contracting party to any product originating in or destined for any other country shall be accorded immediately and unconditionally to the like product originating in or destined for the territories of all other contracting parties.
在服務貿易領域，《服務貿易總協定》第2條第1款規定：With respect to any measure covered by this Agreement, each Member shall accord immediately and unconditionally to services and service suppliers of any other Member treatment no less favourable than that it accords to like services and service suppliers of any other country.