Travelling at an average speed of 300 kilometres per hour, the line will slash journey times linking Beijing in the north with the country's southern economic hub from 22 hours to just eight hours, the China Daily newspaper said.
The December opening means the 2,298 kilometre route, with 35 stops including major cities Zhengzhou, Wuhan and Changsha, will be operational for China's Lunar New Year holiday period, in which hundreds of millions of people travel across the country in the world's largest annual migration.
The specific date was chosen to commemorate the birth of Chinese leader Mao Zedong, state media said.
China's high-speed rail network is booming. Only established in 2007, it has quickly become the largest in the world, with 8,358 kilometres of track at the end of 2010 and expected to almost double to 16,000 kilometres by 2020.
The network has been plagued by graft and safety scandals following its rapid expansion, with a deadly bullet train collision in July 2011 killing 40 people and sparking a public outcry.
The accident - China's worst rail disaster since 2008 - triggered a flood of criticism of the government and accusations that the authorities had compromised safety in its rush to expand.