The exports of rare earth through Shanghai dropped 73.6 percent year on year to 2,542 tons during the first eight months.
As a strategic resource, China had adopted measures to discourage their outflow.
Starting last year, the Chinese government sought to check the outflow of rare earth resources by imposing export quotas, increasing export tariffs for some products and cutting the number of export companies, Shanghai Customs said in an analysis accompanying the data.
"Limiting rare earth exports is strategically important to China. Currently, rare earth is mainly used in the manufacture of precise instruments for medical and scientific uses," said Jia Jinjing, a researcher in Beijing.
"Developed countries like the U.S. and Japan have a great demand for them." However, Jia said that China will probably need them in the future, and therefore must preserve its resources.
According to the Industry Policy Department under China Ministry of Industry and Information Technology, slowed economies in the Americas, Japan, European countries have also demanded fewer rare earth imports.
Japan, European countries, and the U.S. are major importers of rare earth materials, which are mainly used in the manufacturing of precision instruments.
China produces 95 percent of the world's rare earth output. However, China's export prices have dropped to about 60 percent of that in early 1990s, although rare earth demand has risen in 13 areas, including 40 industries like high-tech electronics, lasers, telecommunication, and petrochemical engineering.
"In the future, rare earth will be used more in space technology, the next-generation Internet, and ocean technology," added Jia.
Experts suggest the government begin collecting strategic reserves of rare earth as soon as possible, strengthen the management of exploration, refine and export rare earth, and accelerate the restructuring of various enterprises in the industry.