Mr.rama, the invitation letter from a China company is not sufficient for you to apply for business visa. Your business paertner in China should help you to apply for Original Visa Notice Form issued by authorized departments of Chinese Government, then send to you for visa application.

Besides, the following documents are also required:
1. Valid passport (at least six months before expiration) with blank visa pages and copy of the first three pages;

2. TYPED Visa Application Form (download from https://www.travelchinaguide.com/embassy/pdf/visa-application.pdf) with one passport photo.

3. Applicants who have never been to China before should submit in person.