Paper plates are microwave safe.
However although paper plates are microwave safe they are only microwave safe for around 1 minute to 2 minutes of cooking time.
If you need to microwave something longer than a few minutes then the paper plate could burn.
So if you're cooking or heating something up on a paper plate in a microwave cook or heat the foods in 1 minute increments and check the plate after that.
This way you can tell if the plate is burning or not.
I've microwaved paper plates at 1 minute intervals and never had an issue but I don't normally heat anything up in a paper plate that will take longer than a couple of minutes.
I've even microwaved Styrofoam Plates for 1 minute at a time and they've been okay.
However when I microwaved a Styrofoam Plate longer than a couple minutes at a time it began to melt.
But as long as you only microwave the Styrofoam Plate for only 1 minute at a time it should be okay.
The same is true with the paper plates.
Paper cups and Styrofoam cups can also be microwaved for a minute at a time.