For some foreign country, the official invitation letter is needed to get the visa.
The required documents are as follows:
1 Copies of business license and business registration certificate,
2 Copies of documents related with business, such as import and export documents, bill of lading, contract, bank settlement of exchange, duty-paid proof, etc,
3 Copies of passport and visiting China visa page (if the client has been in China before)
4 Working resume, including invitees' working field and jobs
5 Schedule in China during visiting