This is the Chinese version of Cortana:
Is there any way I can enable it? Changing my phone to Chinese doesn't work.
Cortana is available in China. But the language must be set to Chinese (simplified) or 中文 (简体). Bing translate indiactes that you have set the language to China (People's Republic of China) or 中国（中华人民共和国） which is not supported by Cortana. In case you want to know Chinese (simplified) is located next to China (People's Republic of China).
So go to Settings -> Language and choose 中文 (简体).
Now Cortana should work for you.
Reference : Microsoft.com - Cortana's availablity