The attack occurred around lunchtime in the Minhang District, a suburb of Shanghai.
The alleged assailant was arrested and police opened an investigation. No other details were released.
Of the eight children in hospital, four suffered minor injuries and one was affected more seriously. We will not fear for the life of any of them, according to state news agency New China.
Chinese media report that the assailant was suffering from a “psychotic episode”.
A television station in Shanghai has broadcast images of bloodied children’s clothing.
Daycare centers, kindergartens and schools in China have witnessed in recent years many attacks that left dozens dead and wounded. Strict security measures were put in place to protect children.