The Chinese require "Embassy Authentication" of your no criminal record. It is also called "chain authentication" as everything has to be done in a particular order. It can be as few steps as 3, or as many as god knows what. You first need a no criminal record check, notarized by the police agency that issued it. Mine was the state police of Pennsylvania. Then you need to get an "apostile", which means maybe 2 more steps, mine was one. In the US your state government does this. The apostile verifies the authenticity of the notary. Then, depending on where you live, your national government may have to give their "Department of State" or "Ministry of Foreign affairs" seal on it. After that, you go the the local Chinese embassy or consulate and pay them to put their stamp on it, which is a very impressive stamp I might add. Also you will probably need to have the no crime record translated into Chinese by a translator that the embassy recognizes. When they stamp it, they also bind the whole thing together with a single brass ring..
In the US, there are 5-7 consular districts, you have to use the one that covers your state. Also, the Chinese consulates in the US seem to allow you to skip the national stamp level, and they just took the state stamp. You will have to check with your local consulate.
There are also companies that do all this for you, for a price of course. Just google Apostile, or embassy authentication and you will find a bunch.
Info is available on all this:
Chinese embassy and consulate websites.
United States Office of Authentication
You local state's Department of State
How do I know all this, you ask? My agency's contract brief just mentioned having it "notarized", so that is what I showed up with in China. I got to fly home and do all of the above steps.
Hope this helps