In this paper, using the research method of typology of Architectural Archaeology, three groups of 14 form types and their combination relationships that are helpful for the study of historical stages are extracted from the images of Dunhuang frescoes and the forms of frescoes in 69 caves are systematically sorted out. Through the evolution of balustrade, Wangzhu and Shuzhu, this paper divides the six evolution processes of balustrade from the Northern Wei Dynasty to the Western Xia Dynasty: the first period is the Northern Wei Dynasty, the second period is the Western Wei Dynasty, the third period is the Northern Zhou Dynasty to the Sui Dynasty, the fourth period is the early Tang Dynasty to the prosperous Tang Dynasty, the fifth period is the middle Tang Dynasty to the late Tang Dynasty, and the sixth period is the Five Dynasties to the Western Xia Dynasty. Combined with relevant literature, this paper details the shape characteristics of balustrade in each period.