The strike in the regional capital of Urumqi, in the far-western Xinjiang region, also killed one other person and wounded 79.
It was the third high-profile attack in seven months blamed on Xinjiang extremists that targeted civilians. These attacks, two of them outside the region, have marked a departure from a previous pattern of targeting local authorities.
Police said they had identified two suspects with a history of religious extremism, including a 39-year-old man from southern Xinjiang. They did not explicitly say the attack was a suicide bombing, but said the two men detonated explosives at a train station exit and both died on the spot.
Chinese president Xi Jinping has demanded "decisive" action against terrorism after the attacks.