The 40-year-old woman armed with a kitchen knife and a dagger attacked the two children in Beihai City of Guangxi Zhuang Automus Region this morning.
A three-year-old boy died and a girl aged nine is being treated in the hospital, local authorities said as they did not disclose the woman's relation with the victims.
The suspect was detained and the kitchen knife and dagger were also seized by police, state run Xinhua news agency reported, stating that an initial investigation showed that the woman may have mental illness.
In September, a man killed four students in Guangxi who were on their way to school and fled. The suspect's body was found in the mountains a month later.