The dollar index, which tracks the greenback against a basket of major currencies, rose 0.5 percent overnight as the euro wobbled in the lead up to a policy meeting by the European Central Bank, and retained its gains in Thursday Asian trade.
As such, the People's Bank of China set the midpoint rate at 6.4803 per dollar prior to market open, 0.35 percent weaker than the previous fix 6.4579, ending its three-day firming streak. Traders cited greater volatility in the official guidance rate over the past week.
The spot market opened at 6.4782 per dollar and was changing hands at 6.4768 at midday, easing 0.04 percent from the previous close.
Traders reported bouts of dollar-selling in morning trade, adding that Thursday's weak midpoint had missed market expectations by a small margin.
The State Administration of Foreign Exchange (SAFE) said on Thursday that China would be able to cope with the US Federal Reserve's rate hike policy normalisation, and will push forward with yuan regime reform.
SAFE also added China would promote unified yuan exchange rates in the onshore and offshore markets.
On Thursday, the offshore yuan was trading 0.10 percent softer than the onshore spot at 6.4835 per dollar by midday.