China's trade surplus is expected to decrease to approximately $150 billion this year, the Ministry of Commerce (MOC) said Wednesday.

The world's second-largest economy has already seen its trade surplus decrease this year, and the annual total could shrink by around 30 billion U.S. dollars from 2010 if the downward trend continues, MOC spokesman Shen Danyang said at a press conference in Beijing.

He attributed the surplus drops to the government's efforts to promote trade balance and boost imports.

Shen predicted that annual imports will rise by $360 billion this year, noting that the increase will contribute to global economic growth.

The government will keep expanding imports, he said.

China's trade surplus fell 36.5 percent year-on-year to $17.03 billion in October, far below the expected figure of $25.8 billion.

China's foreign trade may reach $3.6 to $3.7 trillion this year, up from nearly $3 trillion in 2010, Shen said.

Foreign trade in October fell 8.3 percent from September to $297.95 billion, but still rose 21.6 percent year-on-year, according to official data.