The accident occurred this morning in the Xinxiang section of the expressway linking Beijing with Guangzhou in Henan Province, police said.
The truck ran over the barrier belt and crashed the minibuses on the other lane, state-run Xinhua news agency reported.
Twelve people have died, and one passenger is critically injured. Ten others sustained slight injuries, and were rushed to a local hospital. The driver is in police custody, the report said.