The Chinese manufacturing PMI fell to 49.6 in November from 49.8 in October, according to the Chinese government. It was the lowest reading since August 2012.
Analysts had expected the index to remain unchanged at 49.8.
A reading above the 50 mark indicates expansion, a reading below 50 indicates contraction.
The decline was driven by weak demand both at home and abroad for products from China.
The services PMI rose to 53.6 in November from 53.1 in October.