Located in the northern part of the Tibet Autonomous Region, Seni ranges in latitude from 30° 31' to 31° 55' N and in longitude from 91° 12' to 93° 02' E. Bordering counties within Nagqu are Lhari to the southeast, Biru to the east, Nyainrong to the northeast, Amdo to the northwest, and Baingoin to the west, while Lhasa City, the regional capital, is to the south.

With an elevation of around 4,500 metres (14,800 ft), Nagqu has a harsh, alpine climate (Köppen EH), closely bordering on a subarctic climate (Dwc), with long, very cold and dry winters, and short, cool summers.

In winter, temperatures frequently drop below −20 °C (−4 °F) at night and in summer typically rise to 16 °C (61 °F) during the day.

The monthly 24-hour average daily temperature ranges from −11.7 °C (10.9 °F) in January to 9.5 °C (49.1 °F) in July, and the annual mean is only −0.65 °C (30.8 °F).

[3] Seni District is made up of 3 towns and 9 townships:[7]