The mainland's foreign exchange reserves rose to US$151.51 billion at the end of last month, up from $150.4 billion at the end of August, according to People's Bank of China statistics.
The rise would provide more psychological support for the stability of the yuan, the official Xinhua news agency reported.
Analysts said downward pressure on the yuan has eased noticeably following the sharp turnaround in mainland exports in the past three months and a healthy growth in the trade surplus.
Exports last month rose 20.2 per cent year-on-year, the third consecutive monthly increase. That helped bring the trade surplus for the first three quarters to $19.4 billion.
Some economists have predicted the surplus for the whole year could reach as much as $30 billion.