Abstract: In the studies of the Frankish political history in the early Medieval period, more than one hundred years after the death of Dagobert I are traditionally regarded as ″the era of do-nothing kings″(639-751 AD), which means that the Merovingian kings possessed the title of king but wielded no royal power. Since the mid-20th century, with the development of new history, some western scholars have re-examined this point of view from the perspective of text reliability and believed that the last Merovingians were no feebler than their predecessors. However, with an in-depth analysis of the text of the most valuable Frankish historical literature, it is found that the above two views are more or less inadequate. In fact, since the mid-7th century, although most of the kings still held some explicit power, the defects of succession system and a series of problems caused by it were eroding the foundation of the whole Merovingian royal family. It is an indisputable fact that the Merovingian royal power gradually declined in the middle and late periods of the Merovingian dynasty.