The bus was carrying 69 people when it hit the truck on an expressway on Saturday morning, the official Xinhua news agency said.
Xinhua reported that a preliminary investigation showed the accident was caused by a flat tyre on the bus.
Deadly road accidents are common on the mainland, where traffic regulations are often flouted or go unenforced.
According to authorities 58,000 people were killed in accidents across the country in 2015 alone.
Violations of traffic laws were blamed for nearly 90 percent of accidents that caused deaths or injuries that year. (AFP)