The benchmark Shanghai Composite Index went down 2.19 percent to end at 3,115.89 points and the Shenzhen Component Index lost 1.04 percent to close at 10,132.3 points, Xinhua news agency reported.
Total turnover on the two bourses came in at 578.2 billion yuan ($90.9 billion), down from 670 billion yuan on Tuesday.
A preliminary Caixin survey showed on Wednesday that the flash China general manufacturing PMI plunged to a 78-month low of 47.0 in September from 47.3 in August.
The sub-index on manufacturing output retreated to a 78-month low of 45.7 in September from 46.4 in August.
The data showed considerable growth headwinds from soft global demand and the index’s focus on export-oriented sectors had been the biggest reason behind its decline in recent months, given the heavy export-related component in the overall order book, according to Qu Hongbin, chief China economist at HSBC.
Securities shares fell across the board, with Huatai Securities Co. and Guotai Junan Securities down 4.64 percent and 4.4 percent, respectively.
Bucking the trend, cyber security shares rose on Wednesday. Beijing VRV Software corporation surged by the daily limit of 10 percent to end the day at 31.92 yuan.
The ChiNext Index, which tracks China’s NASDAQ-style board of growth enterprises, declined 0.04 percent to close at 2,077.99 points.