BEIJING—China’s rapid trade growth decelerated in September amid weak global demand and a cooling Chinese economy, while its politically sensitive trade surplus narrowed to $14.5 billion.

Export growth fell to 17.1 percent over a year earlier, down from August’s 24.5 percent, customs data showed on Thursday. Imports rose 20.9 percent, down from the previous month’s 30.2 percent.

Demand for Chinese goods has been hurt by Europe’s debt crisis and US economic malaise, while Beijing’s efforts to cool an overheated economy with investment curbs and interest-rate hikes have cut China’s own appetite for imported raw materials and other foreign goods.

China’s weaker demand is a setback for exporters in other nations that are looking to its relatively robust growth to help drive global consumption. Beijing is trying to steer growth that hit 9.5 percent in the quarter ending in June to a more sustainable level. The expansion is forecast to slow to about 9 percent in the latest quarter.

Despite slower growth, September exports appeared to be a new monthly record high at $169.6 billion. Imports were $155.1 billion.

The trade surplus was down from August’s $17.8 billion and well below July’s 30-month high of $31.5
billion.

China’s swollen trade surplus and its export and currency policies are especially sensitive at a time when the United States and other governments are trying to revive growth by boosting exports.

On Tuesday the US Senate approved a bill aimed at pressing Beijing to ease exchange-rate controls that critics say keep its yuan undervalued and give its exporters an unfair price advantage.

It would allow Washington to raise tariffs on imports from countries that manipulate exchange rates to gain a trade advantage. The measure is not expected to become law because it lacks the support of the majority Republican leadership in the House of Representatives, which has yet to vote on it.

China’s foreign ministry responded on Wednesday with a warning that trade ties would be “severely damaged” if the bill becomes law.

Beijing has allowed the yuan to rise gradually in value against the dollar but not as fast as critics want.

China’s September trade surplus with the United States rose 11.2 percent from a year earlier to $19.9 billion, customs data showed. The surplus with the 27-nation European Union, China’s biggest trading partner, fell 7.2 percent to $12.9 billion.