The royal river system of the capital city rivers has a long history. It was the dedicated river channel that Qianlong used to go to Wanshou Temple to pray for his mother's birthday and the royal family went to the Summer Palace. At the time, the two sides were planted with peach trees and willow trees. In the season of spring and summer, the banks of the two banks were full of beautiful green trees and red flowers, leaving the story of "watching pine trees in the Temple of Heaven, watching willows in the long river". It began in Qianlong period and was flourished in Guangxu peridod, sustained during the Qianlong, Jiaqing, Daoguang, Xianfeng, Tongzhi, and the Six Dynasties of Guangxu. It is a special waterway for emperors, empresses, princes, and princes of the Qing Dynasty.