依據路徑依賴理論，每一回合的遞增回報促使了談判路徑的形成，不僅是談判進行的動力，也對決策者產生壓力，因為一旦中途放棄談判除了使遞增回報無法兌現外，談判者還必須承擔談判過程中已付出之時間等沉沒成本，因此對於談判者決策造成影響，使得談判路徑因此一步步形成，最終完成談判。 This paper observes and compares the negotiation processes of the EU-Korea FTA and the U.S.-Korea FTA using the idea of path dependency extracted from historical institutionalism. According to the idea of path dependency, increasing returns is the key to the development of an institution. Since this paper views the final text of an FTA as “institution”, the research sets up three indicators to evaluate the development level of such institution. The three factors of increasing returns are devoted time, expected growth of trade volume, and the completion level of FTA texts. The thesis then calculates the three indicators and obserbs the developing processes of these two negotiation paths. The paper discovers that there’s positive correlation between the level of indicators and the phenomenom of path dependency; namely, the higher the former, the higher possibility of the happening of path dependency.