The HSBC flash purchasing managers' index rose to 51.9 in January, the highest since January 2011 and above the 50-point level that shows accelerating growth from the previous month, Reuters reported.
The PMI, the first preview of China's economic health in 2013, is the latest indication it is steadily recovering from a near two-year cool-down.
"Despite the still tepid external demand, the domestic-driven restocking process is likely to add steam to China's ongoing recovery in the coming months," Qu Hongbin, chief China economist at HSBC, told Reuters.
HSBC said the sub-indices for output, new orders and employment that account for three quarters of the flash PMI all improved in January to hover above 50.
The output index climbed to 22-month highs while the employment sub-index was at its highest since May 2011.
Demand for Chinese exports also improved slightly this month, the flash index showed, but it shed little light on whether the pick-up would last.
The new export orders sub-index rose to 50.1 in January, up from December's 49.2 that pointed to waning demand.