Can we send postcards with US dimensions of 6"x 4" from China? What is the postage rate?

I would like to send postcards made in the USA back to the US to commemorate a cultural exchange from Shenyang, China. However, I believe the dimensions of a regular US postcard (6 inches x 4 inches) is different from those in China. Will China post send those cards to the US or do we need to use postcards in the correct Chinese dimensions? If so, what are those dimensions (in inches or centimeters)? Are there other postal requirements?