The three were sentenced to death and five others were jailed over the attack near Beijing's Tiananmen Square in October 2013 by the court in northwest China's Xinjiang Uygur Autonomous Region, state-run Xinhua news agency reported.
The eight, all hailing from Xinjiang, were arrested after the attack in which a family of three including a mother, son and daughter-in-law were accused of driving an SUV laden with gasoline cans.
Five people, including the three attackers, were killed and several others injured in the attack, which China blamed on the East Turkistan Islamic Movement, a militant group linked to al-Qaeda.
The group has been fighting for the independence of Xinjiang, where the local Muslim Uygurs were restive over increasing settlements of Hans from other parts of China.
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Besides terming it a terrorist attack, few details were released by Chinese investigators.
It was, however, the first such attack outside Xinjiang by the militants.
China had stepped up nationwide security, besides Xinjiang after the attacks.