Eight-year-old Chenggong, or Success, gave birth to a cub at 7:51 p.m., followed by 8-year-old Zhuzhu, or Pearl, who delivered at 6:55 a.m. Sunday, Yang said.
The center currently has 71 pandas in captivity, Xinhua said.
The giant panda is revered as an unofficial national symbol of China. Only about 1,600 pandas live in the wild, mostly in southwestern Sichuan province, which was hit by an earthquake in May that killed nearly 70,000 people.
China's most famous panda preserve, the Wolong Nature Reserve, was seriously damaged in the quake and forced to relocate most of its pandas. The preserve is at the heart of China's gargantuan effort to use captive breeding and artificial insemination to save the giant panda.