The accident happened at about 11 a.m. in Minquan, Xinhua reported.
The bus, operated by Shangqiu Passenger Transportation Group, was heading to Zhengzhou from Shangqiu when it collided with another vehicle, a government spokesman said. The bus, which was carrying at least 34 passengers, then drove into a roadside pond.
Nine people were killed in the incident, while two others were critically injured. About 23 other people were injured, but not seriously, the spokesman said.
The accident is being investigated.