Jiang Tianyong, 46, was sentenced at The Intermediate People's Court in the central Chinese city of Changsha.
Jiang was also deprived of his political rights for three years. He said he would not appeal against the conviction, state-run Xinhua news agency quoted the ruling of the court.
He was found to have made a large number of statements to attack or defame China's government departments, judicial organs and the national legal system, the court ruling said.
"Jiang has long been infiltrated and influenced by anti- China forces and gradually formed the idea of overthrowing the existing political system of the country," it said.
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The court also cited Jiang's role in helping publish information on the plight of another human rights lawyer, Xie Yang, who detailed his account of torture in detention.
Jiang disappeared in November 2016 and it was several weeks before the authorities confirmed he was in custody.
"This case has been an absolute travesty from the beginning, sustained by nothing other than pure political persecution, not facts or broken laws," said Sophie Richardson, China director at Human Rights Watch.
Some were released, but a number of leading lawyers have been charged with subversion, smeared in the party-controlled press.
The ruling Communist Party of China (CPC) in recent years has increased controls over the social media, specially the Weibo, akin to Twitter, which has become immensely popular over the years challenging the monopoly of the state media.
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