There were North and South Shu Mi Yuan (枢密院) in Liao Dynasty, and each of them could be led by two or more Shu Mi Shi(枢密使). The duty of Zhi Shu Mi Yuan Shi(知枢密院事) and that of Shu Mi Shi is the same, and they had roughly the same rank. Indeed, Zhi Shu Mi Yuan Shi is unauthorized Shu Mi Shi. Therefore, when Shu Mi Shi and Zhi Shu Mi Yuan Shi were both in one Shu Mi Yuan, it means Shu Mi Yuan is managed by two governors of the same rank at the same time. The institutional origin of the phenomenon that there are several Shi(使) in Shu Mi Yuan in Liao Dynasty originated from the Five Dynasties. On the one hand, it inherited the tradition of two governors being jointly in charge of Shu Mi Yuan in late Tang and the Five Dynasties, on the other hand, it promoted the rising status of Shu Mi Yuan.