The People's Bank of China (PBoC) said it would trim the so-called "reserve requirement ratio" (RRR) for financial institutions by 0.50 per centage points.
The move came immediately after a G20 finance ministers' meeting in Shanghai, which stressed the use of all available tools to boost growth, and with Chinese and global stock markets assailed by worries over the economy.
The decision also preempted the opening this weekend of the annual session of the National People's Congress, China's rubber stamp parliament.
The RRR cut, which was widely expected by analysts, is the first across-the-board reserve ratio cut since October last year, when the central bank also lowered it by the same margin.
Chinese Premier Li Keqiang is widely expected to declare a lower growth target at the NPC meeting, probably a range of 6.5-7.0 per cent.
The PBoC said in a statement on its website the RRR move aimed at maintaining liquidity and guiding the steady growth of money and credit.
"China still has some monetary policy space and monetary policy tools to address potential downside risk.
