The court in the eastern Chinese city of Nanjing handed down a guilty verdict and sentenced Ma Yohai, 53, to 3 1/2 years in prison, Xinhua news agency reported Friday.
Ma and 22 other defendants were charged with holding group sex encounters at the professor's home.
At the trial, 18 other members of the online swingers' club were sentenced to terms of up to 2 1/2 years, Xinhua said.
Ma said he would appeal the conviction amid calls from supporters for the charge of "group licentiousness" to be dropped.
His club, which had 190 members, consisted of consenting adults who "disturbed no one," Ma said.