Hu Shigen, leader of an illegal underground organization, was sentenced to seven-and-a-half years in prison on Wednesday for subverting State power.
Tianjin No 2 Intermediate People's Court announced the judgment about three hours after it publicly heard the case.
Hu, 61, a native of Jiangxi province who used to teach at a Beijing university, pleaded guilty during the trial.
"It was a fair case hearing. I accept the verdict and will not appeal to a higher court," he said after the announcement.
The verdict said that Hu had been sentenced to 20 years in prison in 1994 for organizing "counterrevolutionary" activities, a charge that was abolished after the Criminal Law was revised in 1997. He was freed in 2008 after his sentence was reduced.
After his release, Hu continued to take part in activities that threatened national security, the court heard.
He used the unregistered organization and paid petitioners to spread subversive thoughts and ideas, asking another suspect, Gou Hongguo, to receive anti-China training overseas, said the verdict.
Hu colluded with Zhou Shifeng and asked Zhai Yanmin and Li Heping to disturb public order by manipulating public opinion, and he established "a systematic ideology, method and steps" to achieve this, according to the verdict.
In February last year, Hu joined a group of 15 people, organized by Zhou and Li, in Beijing's Chaoyang district, discussing how to take advantage of hot topics to stir up the public and providing subversive thoughts.
After a man was shot dead by a police officer at a railway station in Qing'an county, Heilongjiang province, in May last year, Hu urged Zhai to post anti-government opinions online and let him organize some residents to shout slogans and protest at the gate of the county government's offices, the court said.
"Hu told me to call petitioners to go to the county - the more the better," said Zhai, who was sentenced on Tuesday by the same court to three years in prison, with a four-year reprieve, for subversion.
The court said that the verdict was made in line with the law for the defendant's serious behavior of harming the country and for similar charges in the past.
In his final statement, Hu said, "I had long been influenced by bourgeois liberalism and fell deeper into the criminal mire of anti-government groups, although the country educated me a lot to be a college teacher."
"I recognize the severity of my offense and the huge damage I brought to the country, society, my family and myself," he said.
He added that he thanked the government for looking after him while he was ill, and said he hoped to be a law-abiding citizen in the future.
Zhou, Li and Gou are being prosecuted in separate cases.