Officials called the attack, which began around 9 p.m., inside the busy Kunming Railway Station, a terrorist incident, saying it was pre-mediated, organized and vicious.
At least five of the knife-wielding suspects were killed by police but their identities were not confirmed, China's official Xinhua News Agency reported. A Xinhua reporter at the scene said several suspects were in custody.
More than 60 people were taken to hospitals for treatment of stab wounds, emergency officials said.
Last June, a terrorist attack in Lukqun Township in the Xinjiang Uyger Antonomus Region killed 24 people and injured 13.
"Why are the terrorists so cruel?" Chen Cuizhen, a 50-year-old woman who said her husband was killed in the train station attack, told Xinhua. "I found his ID card on his body. I can't believe he just left me."