You can take CNY to China, but you are limited in the value you can bring in accordance with the regulations of the General Administration of China Customs. According to the regulation, passengers who carry over CNY20, 000 in cash or foreign currencies in cash with a value exceeding US$ 5,000 shall be dealt with by the Customs according to relevant regulations currently in force. In the case that passengers carry foreign currencies exceeding US$ 5,000 in cash, and the intension is to take this money out of the country at the end of their stay, the passengers must complete Customs Declaration Forms in duplicate, one copy of which shall, after being endorsed by the Customs, be returned to the passengers for relevant procedures at the time of their exit.

It is quite easy to exchange your currency into CNY at your arrival airports, as well as hotels and banks in China, so it is not really necessary to bring too much currency to China.