reserach conference (i'm from sri lanka)

Sam, you need to prepare those documents containing copy of your passport, the application form with a half-length color photo attached, proof of your financial support, flight itinerary, accommodation arrangement, and an invitation letter from the research conference. After, submit the application to the embassy of China to apply for the entry permit. If the embassy is processed by the embassy, 5 working days are needed; but if the application is transferred to Macau immigration department, 3 weeks may be needed.