We will visit Sichuan and Yunnan next October and we were wondering which current Chinese smartphones available in China are compatible/ (also) working in Europe?

I'm not sure about Europe. But xiaomi works in Canada, shouldn't be a problem in Europe. There is also Samsung here as well.

Yes, the xiaomi works in Europe! You can't get all the apps tho...but I love the xiaomi, I have a xiaomi3, when you buy it, tell them you want to use it in Europe, then it will be fine!

I'm using my MI3 right now in the US on AT&T with no problems.