Muong Ang District was established under Decree 135/2006/ND-CP 14 November 2006 on an adjusted basis of area and population of old Tuan Giao district.

The district has a natural area of ​​44,320.35 ha and 39,851 inhabitants. Northern borders Muong Cha and Tuan Giao district, East borders Tuan Giao district, West borders Dien Bien district; South borders East Dien Bien district and Thuan Chau district of Son La province.

Muong Ang include 1 town and 9 communes:

1. Mường Ảng Town
2. Ẳng Cang (operating area)
3. Ẳng Nưa (operating area)
4. Ẳng Tở
5. Búng Lao (operating area)
6. Mường Đăng
7. Mường Lạn (operating area)
8. Nặm lịch
9. Ngối Cáy
10. Xuân Lao (operating area)