An unknown number of people are believed to be trapped under the collapsed cooling tower platform, reported Xinhua news agency.
According to local media, a total of 68 people were working at the site at the time of the accident.
The Jiangxi provincial fire department said that more than 200 firefighters and about 32 vehicles were deployed at the site.
Rescue operations are underway, searching for potential workers trapped under debris.
The ultra-supercritical power plant is being developed by Jiangxi Energy Group & SDIC Power in Fengcheng, Yichun Prefecture, Jiangxi Province.
The expansion project involves construction of two additional coal-fired power units, each with 1,000MW power generation capacity, The Wall Street Journal reported citing a local government announcements.
Construction work on the expansion project commenced in last July and is scheduled to be completed by early 2018.
In August, a pipeline explosion at a coal-fired power plant in China has killed 21 people, reported Agence France-Presse.
This followed an accident in summer where chemicals leak from a plant in eastern China hospitalized more than 130 people.
