Haidong (simplified Chinese: 海东; traditional Chinese: 海東; pinyin: Hǎidōng; Wylie: Haitung) is a prefecture-level city of Qinghai province in Western China. Its name literally means "east of the (Qinghai) Lake." On 8 February 2013 Haidong was upgraded from a prefecture (海东地区) into a prefecture-level city. Haidong is the third largest city in Qinghai after Xining and Golmud.
Haidong is the easternmost division of Qinghai province. It is bounded by Xining, the provincial capital, to the West, the Datong River Valley to the north, Gansu to the east, and the Yellow River to the south. Mountain ranges tower above the district of which the main valley is the one of the Huang Shui (Tib. Tsong Chu), a major tributary of the Yellow River. This valley stretches from west to east and makes up - together with the area around Xining, the landscape which is called Tsongkha ("Onion Valley") by Tibetans. It has a total area of 13,100 square kilometres (5,100 sq mi)
As of 2005, the total population of Haidong is approximately 1,480,000. It is the most densely populated area of Qinghai, with almost a third of the province's population (its surface makes up only two percent of Qinghai).