What do we need for multi visa requirement for mainland china as a myanmar citizen?

If for company affairs, you shoudl apply for a China F business visa for your staff and an invitation letter of a duly authorized Chinese unit or confirmation of invitation is necessary. You can go to the Visa Office of the Embassy or Consulate -General which holds consular jurisdiction over the state where you reside to apply for the visa for your staff on their behalf, or if they have time, they can also go in person. You may just walk into the visa office during the working hours without any appointment with the required documents:
1. Their valid passport that must have at least six (6) months of remaining validity and at least one blank visa page left.
2. completed Visa Application Forms filled and signed by themselves.
3. one recent photo of 2x2 squre inch (black & white or color is acceptable) each glued or stapled on the application form.
4. invitation letter of a duly authorized Chinese unit or invitation letters from the host company & confirmation of invitation from the local foreign affairs office in China.

It costs $30 for a single entry China visa and takes around 4 working days if you use the normal process.
The visa fee should be paid when collecting the visa.