The manufacturing PMI index calculated by Caixin/Markit fell last month to 49.0, against 49.4 in November, below the threshold of 50 which separates contraction and expansion of activity.
Analysts polled by Archyde.com expected an index of 48.8 in December.
The new orders and employment sub-indices contracted in December.
Weak external demand and slowing global growth weighed on orders from producers of export goods. Logistics problems have lengthened supplier delivery times for the sixth month in a row.
Employment suffered from low production levels and difficulties in finding workers in the context of the epidemic.
The industrial production sub-index, for its part, benefited from the lifting of restrictions linked to the coronavirus epidemic and reached its highest level since February.