I visited china three times for business purpose can i apply now for multiple entry visa

It’s possible for you to apply for a business M type with multiple entries.

The first thing is to prepare the required documents including your passport and copy of its data page, the application form, 2 recently-taken passport-sized color photos, invitation letter of a duly authorized unit, original and copy of business license of your company, home address certificate and its English edition, bank savings account (more than USD4000), non-criminal certificate attested by the Afghanistan ministry of foreign affairs and its English edition, and round trip air tickets. And then submit your application to the embassy of PRC to apply for it.

The stay duration is mainly up to your business travel plan and usually, you may be given 30-day stay duration.