If this experience is closely related to the position you are applying, elaborate on it.

Unless you were representing that company as an agent, delete “on behalf of the company”. “To the public on site” is unnecessary as it is an implied function pertaining to your previous job.

An example for your reference:

“Participated actively in promoting products (every year) in China Export Commodities Fair, setting up visual presentation, engaging potential clients, building up a contact database, conducting market surveys, raising brand awareness…”

Keep adding functions to it if you have done more in the booth. If it is getting too long, then break it up into a neat structure to enhance clarity, maybe in a subset of points.

Orginal: Regularly on behalf of the company to participate in The China Export Commodities Fair to promote products to the public on site

Suggested: Attend the China Export Commodities Fair biannually to present @@@ products and services.

Comments:

1. Start a statement with a verb makes a stronger and more direct statement. The more important thing is to tell what you DO.

2. " On behald of the company " is not really necessary here, if you have already stated your position and employer in a resume (I assume?)

3. " Participate " sounds a bit less involving. Use a stronger verb, "attend".

4. The fair is held twice every year, so be more clear and straight forward, use "biannually". Check if it should be spelled as "bi-annually" or "biannually".

5. "Promote" sounds vague. People attend the Fair to first present products and services by their companies. So "present" contains more information and makes it more clear what you do fundamentally at the Fair.