Gates and Buffett said at a news conference they discussed philanthropy at the dinner and encouraged the wealthy to give to charity, the BBC reported Thursday.
The pair brushed off rumors that some of China's wealthy had been reluctant to attend, saying two out of three people invited showed up. They said no one was asked on the spot to give any money.
"No one was asked in any way, either indirectly or directly, to sign up to anything last night," Buffett said.
"This is a key generation for new China. Today's generation of successful entrepreneurs has the chance to lead and inspire giving for generations to come," he said.