Nanjing Yunjin, inscribed on UNESCO's Representative List of the Intangible Cultural Heritage of Humanity, represents the pinnacle of Chinese silk weaving. Unlike ordinary folk textiles, Yunjin was produced exclusively for the imperial court across the Yuan, Ming, and Qing dynasties — nearly six hundred years. Drawing on published workshop records from the Nanjing Yunjin Museum and the Nanjing Yunjin Research Institute, together with interviews with hereditary masters, this paper reveals the isomorphic structure of Yunjin from three dimensions: institution, craftsmanship, and aesthetics. The institution is the root — it provided sustained demand and resource support; craftsmanship is the branch — techniques such as cut-weft patterning, manual colour-insertion weaving, and pattern-coding were developed within this framework; aesthetics is the leaf — the dragon-phoenix-cloud motif system embodied imperial hierarchical norms. Three institutional barriers — legal prohibition, material monopoly, and cognitive deterrence — rendered Yunjin absolutely non-transgressable. The historical logic of "weaving for the few" made Yunjin's technical knowledge heavily dependent on individual artisans. After the late Qing collapse, the institutional "soil" that sustained this tradition was uprooted. This paper argues that contemporary transmission requires a shift from "individual-based" to "organisation-based" transmission, through systematic reconstruction across four dimensions: institution, education, community, and knowledge management.