"If you looked at industrial production and retail sales, they were showing some recovery but it wasn't a big jump like 51.2 would suggest," Chan said.
China's communist leaders have been trying to reverse a slowdown in which growth hit a two-decade low of 7.5 percent in the latest quarter. But they've held back on implementing broad-based measures.
Instead, China has used targeted measures such as increased spending on railway construction and tax cuts for small businesses to encourage self-sustaining growth and domestic spending rather than trade and investment.
The survey found that factory output grew for a second month, though at a marginal pace. New orders were flat, but new business from overseas customers grew for the first time in six months, with respondents indicating stronger demand from Europe and the United States.
HSBC's report is based on responses from 420 purchasing executives.
An official purchasing managers' index is due out on Tuesday.