Ulaagchinii Khar Nuur National Park (Mongolian: Улаагчийн Хар Нуур) is centered on two large freshwater lakes, Bayan Lake to the west, and Ulaagchin Khar Lake 50 km to the east, in west-central Mongolia.

The particular 'Khar Lake' of this park is in Zavkhan Province, located in a depression west of the Tarvagatai Mountains.

Ulaagchin Khar is surrounded by sand dunes and mountains.

The larger of the lakes, Ulaagchinii Khar Nuur, is freshwater and bordered by sand dunes and local hills to the south.

A number of rare waterbirds have been noted at the site, including the endangered White-headed duck (Oxyura leucocephala), the vulnerable Great bustard (Otis tarda), and the vulnerable White-throated bush chat (Saxicola insignis).