There are four time zones in China. The cities you are looking at are in the same time zone. This happens to be the time zone which most of the Chinese population lives in. An easy way to think about this zone when it comes to knowing what time it is there, at least for me, is that it is always 12 hours ahead of the Eastern US time zone. Hope this helps.

There should be several time zones in China, but the whole country is on the same time - Beijing time!

In fact, we have 5 time zones here. from 75 degrees east longitude ,90,105,120 to 135 degrees east longitude. but we only use the 120 degrees one which is Beijing located in.