The court in the northwest Xinjiang Uighur Autonomous Region said the men had been influenced by "religious extremists."
A fourth man, who pleaded guilty shortly after being arrested, was sentenced to life in prison.
The Xinhua report didn't say to what religious group or religion the men might have been connected, although the Xinjiang region is mostly Muslim.
The court was told how an in-flight fight left two alleged hijackers dead and 24 crew members injured.
The Intermediate People's Court ruled the men were guilty of organizing, leading or participating in a terrorist group, hijacking the aircraft and attempting to detonate explosives on the aircraft.
The aircraft, Tianjin Airlines flight GS7554, took off June 29 from Hotan Airport and was around 870 miles from its destination, the regional capital of Urumqi, when the attack began, Xinhua reported.
The men began shouting "religious extremist cries," the Xinhua report said.
They pounded on the cockpit door until crew members and passengers overcame them.
"Two of the other hijackers, Ababaykeri Ybelayim and Mametali Yvsup, were injured in the fighting and later died despite medical treatment," Xinhua reported.
The men allegedly had been planning the hijacking since May and had detailed knowledge of airport security and the aircraft cabin lay-out.
They were found in possession of tools, including explosives, metal crutches and lighters.
The defendants were allowed to use their native language during the trial, to protect their legal rights, Xinhua reported.
Earlier this year, Beijing said it would leave no stone unturned in its fight against terrorism in Xinjiang, which borders Mongolia and former Soviet republics and is home to the mainly Muslim Uighur people who speak a Turkic language.
Many Uighur say they are unhappy about the large influx of Han Chinese settlers, whom the Uighurs say increasingly marginalize their interests and culture.
In July -- on the anniversary of major ethnic violence -- the top communist official of Xinjiang vowed to strike down terrorists and separatists with "iron fists."
Zhang Chunxian, secretary of the Xinjiang committee of the Communist Party of China, said the situation in Xinjiang is stable, but the area faces "severe challenges."
"We should leave terrorists no place to hide," he said.
Zhang was overseeing a counter-terrorism drill staged by special forces in the regional capital Urumqi to mark the anniversary of the July 2009 riots, a report by China's national news agency Xinhua said.
The government blamed overseas groups for inciting the riots which killed nearly 200 people, a report by Xinhua said at the time.
Amnesty International has said it believed "dozens, if not hundreds, of the Uighur ethnic minority, many of whom were arrested in the wake of the riots, are still disappeared."