Your employee can apply for Business Visa to China(https://www.travelchinaguide.com/embassy/visa/business.htm) the below documents are required:
1. A valid passport as well as a copy of its information page.

2. Application form: One neatly completed Visa Application Form (Form V.2011A) with genuine information and signature.

3. Photo: one recently-taken color photo of 2x2 square inch glued or stapled on the application form.

4. "Invitation Letter of Duly Authorized Unit" or "Confirmation Letter of Invitation", or invitation letters from the host company, meeting or exhibition organizers in China, or an introduction letter from your US company, etc.