do i need to obtain travel insurance on a 12 day business trip to china on L type.

Hi, first of all, you need to apply for a business F if you are visiting for business purpose. L is not sufficient and not a correct type for this visit.

About the travel insurance, it is not mandatory. For business visit, you should provide Qualified original invitation & guarantee letter with signature and stamp from your sponsor and business partner, and Qualified original introduction letter with the full name, title, date & signature of the issuing person from your company, and any proof of business connection with the inviting company.