Qianlong Lake, The largest artificial ecology waterbody in the Expo Park, is transformed from a fishpond and its water cycle is carried out through connected culvert. There are calamus, cattail, versicolor, cyperus alternifolius and reika and other aquatic plants in the water. The lake achieves water purification through biological degradation. The lake can also collect rainwater from the surrounding slopes to form a small system of natural wetland water circulation. It is a model of the water ecology cultural construction of Expo Park and a place for leisure, recreation and ecological science.