An official at the coal mine safety administration in Linfen, the city where the mine is located, confirmed the accident and that men were trapped but declined to provide any further details, the AFP news agency reported.
The Wangjialing mine belongs to the state-owned Huajin Coking Coal company.
It was undergoing infrastructure construction when the flooding trapped the miners.
The mine covers about 180sq km while the mining zone holds more than 2.3 billion tonnes of coal reserves, including nearly 1.04 billion tonnes of proven reserves, Xinhua said.
It is expected to produce six million tonnes of coal each year once put into operation, according to Huajin Coking Coal's website.
China's coal mines are among the most dangerous in the world, though the number of deaths has been declining.
The number of people who have died in Chinese coal mines dropped to 2,631 in 2009 - an average of seven a day - from 3,215 in 2008, according to official statistics.