The Purchasing Managers Index or PMI for manufacturing came to 50.8 in May, up from 50.6 in April.
Numbers above 50 indicate growth. Below 50 indicates a contraction.
China's officials Xinhua news agency reported Saturday the index has remained above 50 for eight consecutive months.
Although gains are modest, market analyst Zhang Liqun at the Development Research Center of the State Council, said the eight-month stretch shows the overall economic recovery has been persistent.
The PMI is a composite of several component indexes. In May, the production index rose from 52.6 to 53.3. New orders added 0.1 percentage point to 51.8 percent.
The index for raw material purchases gained 5 percentage points to reach 45.1. Indexes for inventories of finished goods, purchasing prices and purchasing quantity all showed gains. But the index measuring the number of employees declined 0.2 percentage points to 48.8 percent.
The official PMI figures are from the China Federation of Logistics and Purchasing, which bases its numbers on a survey of 3,000 businesses. The results, however, are more optimistic than the flash estimate of the manufacturing PMI released by HSBC last week.
In a preliminary estimate, HSBC pegged the PMI at 49.6 for May. The bank issues its final estimate for May Monday.