Miyun Reservoir, located 13 kilometers north of Miyun County in Beijing, is located in the hills of Yanshan Mountains. It was built in September 1960. With an area of 180 square kilometers, Miyun Reservoir has a capacity of 4 billion cubic meters and an average water depth of 30 meters. It is the largest and only source of drinking water in Beijing.

The water of Miyun Reservoir comes from two rivers, Baihe River and Chaohe River. Miyun Reservoir is the largest artificial lake in Asia, known as "the Pearl of Yanshan". There is also a 110-km long highway around the reservoir, which is one of the scenic spots in Beijing. The average temperature in summer in the reservoir area is 3 ℃ lower than that in the urban area, so it is a summer resort.