What visa to use if applicant is a korean but work here in the philippines

Business Visa or Tourist Visa should be ok.

no. of months we can get
Good morning! thanks dante for your prompt reply. Is it possible to get 6 months visa?

It is hard to get a business visa or tourist visa with 6 months stay duration in China, I'm afraid that your boss can only gets a 3 months single entry visa with 30 days stay duration.

If he applies business visa, the supplier company in China should send him an invitation letter with the copy of business license and an offiical invitation letter issued by local Foreign Affairs Office.

It is easy for him to get a tourist visa to China if he can't provide the invitation letters.

please check, there is new provision, they allow south korean for visa free entry to china , this i just heared from korean friends

It is not true, Korean nationals (Korean ordinary passport holders) don't enjoy visa exemption to Mainland China. Citizens of Singapore, Brunei and Japan holding ordinary passports may enter China without a visa through the ports of entry open to foreigners provided that they come to China for tourism, family visit, business or transit, and intend to stay in China for no more than 15 days.

If you hold a Korean diplomatic, official/service passport, you don't need a visa to Mainland China for up to 30 days.

Has he been to China before? Is he a resident in Philippines?
Get a business visa or tourist visa should be ok.
Ask if your supplier can provide you requirement paperwork