The knife attack occurred at a urology hospital in Huizhou City.
The 26-year-old suspect, surnamed Lai, has been controlled by police.
The nurse was killed while a security guard and three other medical workers were injured. The injured have been hospitalised and are in stable condition.
The suspect's motive was not known and police were investigating the case, state-run Xinhua news agency reported.
Attacks on medical personnel by patients and their relatives have become common in China.
The government has ordered stepping up of security in all hospitals in the country.