I live in Europe and I am Chinese.
I tell you what will be the first problem you will meet after you are in China.
"Foreign exchange controls"
http://baike.baidu.com/view/433566.htm (open your google translate)
So in principle if you want bring more than 5000 USD or equivalent EUR cash out from China.
You need report it to Chinese customs.
If less than 10k more than 5k USD you need permit from "Sate Administration of Foreign Exchange".
(There is English section under
http://www.safe.gov.cn/)
Nobody knows how can you get a permit from SAFE even for a legit business in China.You can try to tell them you are trading BTC (just kidding).
If you didn't report it in airport and their x-ray find you, then you have to explain and hope they accept your story.
Sure China is a country where everything is possible but then you need try your luck and figure out how everything become possible.
Even you are a foreigner who lives in China when you go to convert your CNY to EUR in bank they want see your income certificate to make sure you don't convert more money than you earned.
In fact even some foreign companies has trouble to send their profit out of China.
Why China makes it so difficult to transfer foreign currency out? I don't know maybe the 3.3 trillion foreign exchange reserves isn't enough for our government.