Some factories were ordered to shutdown to improve air quality
A slowdown in the growth of demand for Chinese goods from overseas caused industrial output to ease in July, official figures showed.
The National Statistics Bureau said the output from China's factories was 14.7% higher in July compared with a year earlier, down from 16% in June.
It is the slowest pace of growth for 18 months and reflects a slowdown in the global economy, the bureau said.
Some factories were also shut to ease pollution ahead of the Olympics.
The Chinese government ordered some factories to suspend production from the end of July in an attempt to improve air quality.
Economists are expecting output to pick up again after the Games.
"The figure will intensify the market's worry about an economic slowdown," said Lu Zhengwei, chief economist at Industrial Bank in Shanghai.
"Things will improve a little after the Olympic Games as Western countries place orders to prepare for Christmas."