The bus, carrying 36 passengers had fallen into a valley in northwest China's Xinjiang Uygur Autonomous Region yesterday.
It was on its way to a tourist spot near the city of Changji in Changji Hui Autonomous Prefecture.
Four people died at the scene, while another 11 people succumbed to their injuries in the hospital.
The other 21 passengers sustained injuries and are still being treated, said Wu Jun, executive vice major of Changji, state-run Xinhua news agency reported.
Heavy fog that reduced visibility has been blamed for the accident.