besides passport,what doc Canadians need when travel by air to Mexico?

that's it. On the flight to Mexico, you'll be given a tourist visa form, which you fill out and is good for 180 days. Upon landing in Mexico, an immigration officer will stamp it and sign after you show your Canadian passport.

Make sure you keep your tourist visa (the one they'll give you on the plane) at all times while traveling in Mexico. Keep it tucked in your passport. You'll need it to leave the country

Your PR card and Id.

A gun and full body armor