The three were accused of providing funds to carry out the October 28 attack, in which a car ploughed through tourists and crashed in a fireball in the heart of the capital, killing two bystanders and the three attackers.
A court in the Xinjiang regional capital of Urumqi sentenced the three to death. Five other people were given prison sentences, with four receiving terms of five to 20 years and one getting a life sentence.
The court heard they had travelled to Beijing on October 7 to deliver money to buy a vehicle, petrol, knives and other materials related to the attack.
A Chinese visitor and a tourist from the Philippines were killed in the attack.