The new trees, many planted by volunteers, covered 80 million acres, Jia Zhibang, director of the State Forestry Administration said at a news conference in Beijing on Monday.
China has been trying for more than a decade to reverse the rapid loss of what little remains of its forests.
Experts blame heavy tree-cutting, spurred by rapid economic growth, for the loss of farmland to deserts and devastating summer flooding in areas where denuded hillsides fail to trap rainfall.
Tree-planting in northern China has helped to reduce the severity of the spring dust storms in Beijing and other northern cities.
The trees planted in 2001-2005 raised the portion of China covered by forests from 16.5% to 18.2%, and the government hopes to raise that to 20% by 2010, Jia said.
The amount of China covered by what outsiders would consider forest is usually smaller than reported because the government figures often include fruit orchards and other territory with trees.
The government also hopes to increase the amount of vegetation in China's densely crowded cities, Jia said.