The panda dubbed Haizi gave birth to the two cubs 10 minutes apart Saturday, workers at the China Conservation and Research Center for the Giant Panda at the Wolong Nature Reserve said.
The firstborn cub appears to be healthy, they said, based on its size and the volume of sound it is making. The second cub is slightly smaller but also appears healthy, they said.
Haizi got pregnant after mating with two male pandas in March, China's state-run Xinhua news agency reported.
Most giant pandas are not good breeders when in captivity and remain sexually inactive much of the time, officials said.