China's top five State-owned power generators' total profits hit 74 billion yuan ($12.21 billion) last year, a record high since 2002, thanks to falling coal prices.

China Huaneng Group, one of the five giants, realized profits of 20.84 billion yuan, ranking the top followed by China Guodian Group Corp, China Huadian Corp, China Power Investment Corp and China Datang Corp, Securities Daily reported on Friday.

Cao Peixi, general manager of China Huaneng Group, said the structural adjustment is the key of accelerating development, and the company will continue to improve its quality and efficiency this year.

"The company will actively develop low-carbon energy and improve its existed coal-fired power plants to achieve higher efficiency," he said.

According to the company's statement, clean-energy power accounted for 27.5 percent of its total installed capacity.

Last year, Huaneng generated 639.7 billion kilowatt-hours, up 7 percent year-on-year.

Domestic coal prices have been declining since the second half of 2012.

In the beginning of January, coal prices dropped to below 600 yuan ($100) a metric ton because of weak demand and excessive supply in China.

Most Chinese coal companies suffered losses last year, according to China National Coal Association. Up to 33 companies, or 36.7 percent of all Chinese coal companies, were in the red from January to November last year. They lost 40.55 billion yuan during the period.

Jiang Zhimin, spokesperson for the association, said the situation won't improve much this year.