| Dalanjargalan District | |
| Native Name: | Даланжаргалан сум |
| Native Name Lang: | mn |
| Settlement Type: | District |
| Subdivision Type: | Country |
| Subdivision Name: | Mongolia |
| Subdivision Type1: | Province |
| Subdivision Name1: | Dornogovi Province |
| Area Total Km2: | 4,045.90 |
| Timezone: | UTC + 8 |
| Utc Offset: | +8 |
Dalanjargalan (Mongolian: Даланжаргалан, Seventy happiness also Ulaantolgoi)) is a sum (district) of Dornogovi Province in south-eastern Mongolia. Sum center is Olon Ovoo railway station on Trans-Mongolian Railway (Ulan Bator - Beijing) line and abandoned Soviet air force base location. Eldev Coal Mine is 21 km N from sum center. In 2009, its population was 2,554.[1]