If he has a working visa of none-Chinese country, he can register as a foreigner, free. Or must come with a foreigner, and register by pay about 300RMB /day.
https://www.cantonfair.org.cn/en-US/posts/602072867751886848
https://www.cantonfair.net/canton-fair/canton-fair-registration
->Registration Documents Requested Table ->Representatives of Foreign Company's Representative Office in China
- Copy of Business Registration Certificate of Foreign Company's Representative Office in China
- The Employee's ID Card & Copy
- A most recent personal photo
- Name Card
300RMB /day plus another 30 RMB/card as service fee must be paid besides presenting the requested document. Only one local representative is allowed for each overseas company and must be accompanied and signature-confirmed by buyers of a relative overseas company)