Ping'an District formerly known as Ping'anyi, is an administrative district and the seat of the city of Haidong, in the east of Qinghai Province, China, located about 35 km (22 mi) east from Xining. Its postal code is 810600, and its population is 127,480, 29.4% of whom belong to ethnic minorities. The area is known for its Selenium resources.

Haidong 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 most populous administrative division in Qinghai after Xining and Golmud.