Multiple transit in China

I have a mexican passport. I want to travel from Vancouver to Auckland doing two stops in China. This is the itinerary:

Vancouver to Zhengzhou, 6 of November, with 2:55 hrs wait
Zhengzhou to Chengdu, 7 of November, 5:35 hrs wait
Chengdu to Auckland, 8 of November

Do I need to get a visa before I take any flight???