The mine is in the Ili Valley in the Xinjiang region near the Kazakh border.
The region's geology and mineral resources bureau said it holds at least 53 tonnes of gold worth about $3.2 billion. It also holds about 31,200 tonnes of copper worth $230 million.
By the end of 2015, the mine is expected to start production and is projected to put out 3 tonnes of gold annually.
Although it is the second mine discovered in the valley, it is the largest one found in the region's Tianshan Mountains.
The area falls within the Narat-Hongliu River metallogenic belt suggesting more precious metals will be discovered.