Analysts say it is part of a strategy by the Khartoum government to deal with the loss of oil revenue following the session of South Sudan last year.
The country has great mining potential, but overall production figures are hard to verify because unofficial miners account for a large part of the gold industry, the agency says.
The new refinery, which will also process silver, is intended to reduce the amount of gold smuggled to other markets, such as Dubai, as producers should receive more money for higher-quality gold, it says.
"The refinery is the first project of its kind in Sudan and the second in Africa for producing and extracting gold and silver with high quality and purity," China's official Xinhua news agency quotes the director of the refinery, Mohamed Hassan Osman, as saying at the inauguration.
Another refinery director, Azhari Altayeb, said the plant would also process gold from countries in the region such as Egypt, Eritrea, Chad and the Central African Republic, reports the Sudanese Media Center, a website which has close links to the government.