This paper discusses the essence and formation of the Monthly Archives of the Eight Banners and the connection between the Monthly Archives and the Veritable Records of early emperors / Khans in the Qing dynasty. Evidences show that the compilations of Monthly Archives by two Banners of the same major colors were officially formed at least in the beginning of Hong Taiji's reign. As a sample archive of 1631 reveals，Monthly Archives recorded various events of the later Jin dynasty by focusing on the speeches and actions of Grand Khans on daily basis. These archives were officially preserved in the Literate Institute，and were compiled together in different subjects by Manchu literati officials. Together with inter-state documents，these archives became original sources of the later Veritable Records and other official history compilations. Although the Monthly Archives had long been considered missing，these archives could be closely related to the three early Veritable Records compiled in 1636 and Shunzhi reign.