The trio were among 15 weightlifters who tested positive for a variety of banned substances after the International Olympic Committee (IOC) re-tested samples using methods which were more advanced than the ones available at the time.
The 15 have all been provisionally suspended, the Budapest-based IWF said.
The gold medallists were Chen Xiexia, who won the 48kg category, Liu Chunghong (69) and Cao Lei (75).
Chen lifted 13kg more, Cao 16kg more, and Liu 31kg more than their closest rival -- in a sport where there is often just a single kilogram between gold and silver.
Eleven weightlifters from the Beijing Games had already been suspended in July after testing positive.
One medal, the silver won by Turkey's Sibel Ozkan in the 48kg, has already been stripped and will be reallocated.
(Writing by Brian Homewood; editing by Sudipto Ganguly)
