Need transit visa in guangzhou

Hi, I hold Vietnamese passport. I bought the ticket fly from Ho Chi Minh city to Christchurch New Zealand and transit in GuangZhou 5 hours from 7.30pm and start another fly at 12.50 am next day by Southern China Airline. I just wonder do I need transit visa in Guangzhou if dont leave the airport. I want to make sure before flying. Dont want get stuck in Guangzhou.

Thank you very much for your help.