For China Business Visa to whom i have to write a letter?

For China Business Visa to whom i have to write a letter ? Or does letter is issued by the company in China ?

I am not the permanent resident in Hong Kong ( I have a dependent visa ), I am working in China in chinese company. I usually have to travel from hong kong to china its quite difficult for me to travel often and to get a visa for china.So i am planning to apply for China Business Visa.

For China Business Visa to whom i have to write a letter ? China Embassy ??????? Or Do i have to write a letter or is it issued by the company in China for whom i works for ?

Please reply