Abstract: Tang Yang means building model sample of building in Qing dynasty. Tang Yang in the Forbidden City was used to be submitted to the emperor for preview. A Tang Yang can show the all-around information of a Qing dynasty building such as appearance, constitution, decoration, color and so on. The Tang Yang of Yanxi Palace indicated that the building characteristics of Lingzhao Veranda in Qing dynasty were very similar to those of other buildings in the Forbidden City. The Tang Yangs in the Forbidden City were made by Lei family, whose members of 7 generations contributed the design and construction of the emperors’ buildings in Qing dynasty. The scientific value of Tang Yang is that it can truly reflect the building information, its manufacture and installation are also convenient. Besides, it provides valuable historical information for buildings of Qing dynasty, and deeply represents the architectural culture of the palace buildings in Qing dynasty.