The blast occurred on Monday evening at the plant in Zhangzhou. State news agency Xinhua reported one injury.
The plant produces paraxylene (PX), a flammable chemical used in polyester and plastics manufacturing.
The location of PX plants in China has sparked protests from residents, including violent demonstrations last year in Guangdong province.
Many residents fear pollution from the plants is hazardous to health.
The South China Morning Post reported that this was the second blast at the plant in two years.
The plant in Zhangzhou is operated by Dragon Aromatics, one of the largest independent PX producers in China. It has not yet commented.
China Central Television (CCTV) carried footage of the fire, with flames shooting into the air, but provided few details.
Xinhua said the blast occurred at about 19:00 local time (11:00 GMT) in a pumping station.
Facts: Paraxylene (PX)
Basic raw material which when refined is used to make polyethylene terephthalate (PET)  polyesters
The fibres and films produced are used to make water bottles, other containers, fabrics including clothing and curtains, and x-ray and photographic film
Can cause dizziness and nausea if inhaled or ingested. If skin is contacted, it should be rinsed and then washed with soap and water. Can cause issues with the central nervous system
The Zhangzhou fire department said about 430 fire-fighters were at the scene.
The Post quoted one resident who lives across the harbour from the plant, about 10km (six miles) away, who said his flat shook with the explosion.
Lin Chen told the paper: "I heard a loud bang at home. Everyone in my county saw it. The plant was burning. We can still see it. But I don't smell anything weird now. I think it's because we're upwind."
Protests remain rare in China, where it is illegal to demonstrate without a permit, but environmental campaigns are growing in number.
In recent years paraxylene has become a focus of such protests, forcing the delay or cancellation of plants, much to the dismay of the national government, correspondents say.
A protest about a PX plant in Maoming, in southern Guangdong province, turned violent last April, with tear gas fired and several demonstrators injured.
An explosion has ripped through a chemical plant in south-eastern China's Fujian province, sparking a major fire.