The China Conservation and Research Center for the Giant Panda in Sichuan province said the panda named Haizi gave birth to the two cubs 10 minutes apart on Saturday.
Staffers at the center, which is part of the Wolong Nature Reserve, say one cub is a female and weighs 79.2 grams (2.79 ounces). Haizi has yet to release the other cub from her embrace.
Giant pandas have difficulty breeding, with females fertile for only two or three days a year.
Pandas number about 1,600 in the wild, where they are critically endangered due to poaching and development. More than 300 live in captivity, mostly in China's breeding programs.