Abstract:Taking the drainage systems of the three capitals of the Bohai Sea Kingdom of the Tang Dynasty as the research object, and taking into account the relevant archaeological work in recent years, this paper analyzes the planning and layout of the drainage systems of the three capitals and the structural mode of some drainage measures, it shows that the drainage system inherited the idea of arranging water from the Tang dynasty while maintaining the construction features of the local characteristics. It also reveals that the Bohai Sea State was a frontier region of the Tang Dynasty and a marginal area of traditional Chinese culture, its capital drainage system reflected in the construction of the geographical environment response and response to cold climate response.