The official manufacturing purchasing managers' index (PMI) stood at 48.0 against 49.2 in October, the lowest reading in seven months, according to data from the National Bureau of Statistics (NBS).
Separately, the non-manufacturing PMI, which looks at service sector activity, fell to 46.7 from 48.7 in October, also the lowest reading in seven months.
Chinese authorities this month rolled out a flurry of policies to prop up the struggling economy, including reserve requirement ratio cuts and COVID fine-tuning measures, while loosening financing curbs to rescue the property sector.
The official manufacturing PMI largely focuses on big and state-owned firms.
The private sector Caixin manufacturing PMI, which centres more on small firms and coastal regions, will be published on Thursday.