The teacher, Wang, at the Wuyang Minzu Junior High School in Hefeng county, is under investigation, county public security bureau officials told Xinhua.
The teacher has been detained and is under investigation.
An online post Tuesday alleged that Wang had forced sex with at least eight third-graders at the township junior high school, one of whom became pregnant.
The post stated that the victims were too scared to reveal the abuse and it came to light only when one of the girls became pregnant.
Hefeng is a mountainous county in western Hubei where a large number of children are "left behind" in their hometowns by parents who work as migrant workers in cities. These children are easy targets of sexual abuse and violence.