Orkhon aimag is located in Central Mongolia, bordering with Selenge aimag to the east, Bulgan aimag to the west. Orkhon aimag is situated in the forest-steppe sub region of Khangai Mountain region, occupying the midlands of Buren mountain range and Orkhon and Selenge river basin. It is surrounded by Erdenet-Ovoo, Bayan-Undur, Deeliin Nuruu Mountains which are elevated at 1,600 to 1,700m above the sea level. Majority of the mountains in this aimag are medium high mountains. Orkhon is considered to be the smallest aimag of Mongolia.

Orkhon aimag has a continental climate. Winter season is very cold, starts in early November and ends around in the end of March. The lowest ever a recorded temperature is -40°C and hottest is +39°C. On average, temperatures drop down to -20°C and increases up to +30°C. Mostly calm, stable weather dominates the region. Annual average air temperature is +0.8°C and average precipitation is 371.8m in a year with high rain and snow falls. April and May are the windiest months, January is the coldest and July is the hottest month of the year. Wind speed reaches to 28m/sec occasionally. During the rainy times precipitation rate can increase by 80% or reaches 250 to 300mm. Orkhon aimag, situated in Sothern valley of Buren mountain of Khangai range, surrounded by 200-500m high Erdenet Ovoo, Bayan Undur, Delen mountains, has a unique microclimate.

The soil consists of the steppe, desert-steppe, and mountain umber powder like soil with carbonate. One of the 10 biggest copper deposits of the world is located in this aimag. Erdenetiin Ovoo Mountain of Erdenet city that lies in Orkhon and Selenge Rivers basin, is rich with copper and molybdenum. Erdenet Copper and Molybdenum Concentration Plant started its operations in 1978. The copper ore ledgement stretches for 25km to the north with the width of 1.5 to 3km. Erdenetiin Ovoo Mountain used to be 1,607m in height before the exploitation.

Orkhon aimag was established as Erdenet city in 1976, in the territory of Bulgan aimag. Nowadays Erdenet city is the capital of Orkhon aimag, one of the biggest mining industrial centers of the country. Erdenet City is elevated at 1,200m above the sea level forming its own micro-climate. Orkhon aimag was established in 1992 with 2 sums, Bayan-Undur and Jargalant. Since then Erdenet city became the capital of Orkhon aimag. In Erdenet city, Mongolia-Russia joint venture Erdenet Mining Corporation, Copper and Molybdenum Concentration Plant is located. And also many other factories like carpet factory, food and beverage factory and metal processing factory is located in Erdenet city. The city is connected to the capital city of Ulaanbaatar by paved road. 

Since the center of the aimag, Erdenet city, is located in the area of Bayan-Undur sum, this sum area can also be considered as the part of the city. Erdenet city is divided into 3 regions, apartment region, ger district region and factory region.

Over 20 million tons of copper concentrate annually, mine blasting products and steel ball for crushers are produced here. Mongolia-Russia joint venture Erdenet Mining Corporation, Copper and Molybdenum Concentration Plant is one of the biggest of its kind in Asia with its mining and concentration outcome. In 1978 the "Erdenetiin Ovoo Deposit" plant was established in the area by the contract signed between Governments of two countries. This deposit is located at 340km northwest from the Ulaanbaatar, 180km west from the Darkhan City, 60km north from the center of the Bulgan aimag and 140km from the border of the Russian Federation. The plant is connected to the East Siberian Railway at Naushki Station and to the Chinese Railway at Erlian (Ereen) City. 

Erdenet Plant has established collaboration with the leading mining and metallurgy organizations of the world. Erdenet Plant is a Mongolia-Russia joint venture, the 51% of shares are owned by Mongolian Government and 49% of shares are owned by the Government of the Russian Federation. Currently, the Erdenet plant is processing 25 million tons of ore per year and producing over 530 thousand tons of copper concentrate and 3 thousand tons of molybdenum concentrates annually.