國在中國的保教權自1920年代已漸趨式微，1926年10月，宗座代表剛恆毅促成教宗庇護十一世在羅馬祝聖六位中國主教後，法國的保教權更是搖搖欲墜。1926-1928年國民政府北伐，對中國內政及其與教廷的外交互動，均造成根本上的變化，也間接影響到法國這項特權。本文即著眼於1928年6月到翌年3月北伐結束前後時期，以剛恆毅為中心，根據法國外交部檔案及剛氏個人回憶錄，探討梵、法在華保教權之爭，及其牽涉的梵、法、中三國外交關係。首先論述保教權對法國的意義，其次分析法、梵兩方對這項權利的立場與態度。而後則考察1928年中教宗公開致函中國教會與中國頒布新土地法規兩事件，並將其所引發的梵、法、中三邊連動關係，與1929年初中梵雙方極力推動簽訂〈政教協定〉而終歸失敗一事相扣，凸顯法國以外交手段鋪天蓋地打擊剛恆毅、教廷和中國政府，不到最後一刻絕不輕言放棄保教權的過程。結論指出，教廷鑑於中梵發展進一步關係的時機尚未成熟，終仍同意暫時繼續承認法國在華的保教權；而剛氏的活動看似失敗，然實已為中梵關係的未來發展預先鋪路，應予高度評價。

The French Protectorate showed signs of decline beginning from the 1920s, and appeared on the verge of collapse after the consecration of the first six Chinese bishops in Rome by Pope Pius XI in 1926. This article explores the topic by looking at the accomplishments of the Northern Expedition of the Nationalists from mid-1928 to March 1929. The actions of the Apostolic Delegate, Celso Costantini, constitute the central part of this study, allowing us to discern the basic features of the dispute between the Holy See and France over the French Protectorate in China. This article demonstrates the processes by which France exercised its influence to incessantly oppose the plan of a Concordat between China and the Holy See. Three major issues are explored: the policies of the Holy See and France toward the Protectorate, the reasons of the failure of the plan of the Concordat, and Costantini’s achievements during this period.