唐代成德軍爲安史亂後河北跋扈藩鎮之一。學界傳統上對河北落鎮多作「一整體性」之研究。本文計劃以研究西元781年起之成德軍分裂事件，藉此探討河北內部各勢力，彼此間存在政治利害關系並相互政治利用、競合，故唐代河北問題，實也並非絕對是以往史家所觀察到的一整體性問題。本文計劃探索究竟是什麽原因促使成德軍分裂？又是什麽原因使分離出的易定、橫海雨小藩鎮日後會採取恭順於朝廷之政治立場，而不隨其他河北藩鎮般跋扈於朝廷？以上爲以往史家常忽略之問題，本文冀能藉此研究，鷔清此間歷史之真相。至於本文時間斷限，則始於西元781年成德軍第一任節度使李寶臣甫逝世，其下諸勢力彼此分裂開始，至西元789年朝廷正式設立滄景使爲止。

Chengde Jiedushi（成德節度使） was one of the most powerful and rebellious governors after the An-Shi Rebellion（安史之亂）in the Tang Dynasty. Since most scholars have dealt with overall research, the author would like to examine specifically the split of the Chengde Jiedushi by dealing with the powers in the Hebei(河北) area, which inter-depended while competing each other for political advantages and brought with various effects. The author also would like to discuss the reasons why the Chengde Jiedushi split and why the two sub-cliques from the Chengde Jiedushi, Yiding（易定） and Henghai（橫海）,decided to obey the central government instead of following other powers against the throne. The article starts from 78lAD, which began a series of split following the death of Li Baochen（李寶臣）, the first governor of the Chengde Jiedushi, and ends up at 789AD, when the central government formally set up the Cangjing Governor（滄景）。