The HSBC flash purchasing managers’ index (PMI) for December edged up to 50.9, above the critical 50 level which separates growth from contraction.
The reading marked the highest level since October 2011 and the fifth consecutive monthly gain.
The flash survey provides a further sign that Chinese growth is reviving.
The improved conditions were primarily driven by domestic demand, said Hongbin Qu, China chief economist at HSBC. The new export orders index fell, adding to the surprisingly weak export growth in November customs figures to suggest China faces "external headwinds", he said.