A grad school degree in China will only be useful in China, or if the schools in your country have a worse education system than the one in China.
A graduate degree in the USA, especially something like a MBA from a top university in the USA, would be useful both in the USA and China (as well as other countries).
Note that if he already has a degree from a top university in the USA then the graduate degree is of lesser importance.
By "top university" I mean a name that an average non-US person would recognize.