In the Qing Dynasty, the Wanquan River basin was densely covered with a water network, and its abundant water sources and superior geographical conditions nourished the garden clusters in the northwestern suburbs of Beijing and became a key element in the construction of gardens in the “Three Mountains and Five Gardens” area of Haidian. The garden construction in the Wanquan River basin reflects the close integration of garden waterscape construction and urban water resources utilization. The article sorts out the history of the Wanquan River basin in the Qing Dynasty, combined with the natural conditions of the basin and the general situation of water resources, through literature research, graphic analysis, and other methods, summarizes the coupling of water source regulation and storage and garden construction; the synergy between water conservancy engineering and garden water management; the unification of water quality conservation and waterscape construction are the characteristics of garden water management in the basin. The traditional wisdom of water management is summarized and applied in modern urban construction through the combing and exploration of the water management techniques in the Wanquan River basin. Then, from the three perspectives of the integrity of the style, the authenticity of the heritage, and the practical function, it explores how to protect and inherit the landscape system composed of the ancient garden.