The bus carrying 61 passengers broke through a central partition on the highway and ran into the opposite lane to crash with an oncoming semi-trailer truck in Guazhou County in the city of Jiuquan, state-run Xinhua news agency reported.
Eleven of the dead were the bus passengers while two were in the truck. The number of injured is still being verified.
The overloaded 55-seater bus was carrying seven children.
The bus, owned by a company in Urumqi, capital of the far western Xinjiang Uygur Autonomous Region, was en route from Miquan in Urumqi to Guyuan in Ningxia Hui Autonomous Region when the accident took place.