I have been invited to present my paper which visa should i apply ?

Hi, you need a F visa.

The following documents are needed when you applying visa:
1) Application Form with a recently-taken color photo glued or stapled on
2) Valid passport and a copy of information page.
3) The invitation and acceptance that you recieved;
4)Personal Written Statement (Covering Letter,with details as follows: A. name of the scenic spot; B. name, address and contact number of the inviting(contact company or person).
5) Other documents required by the Chinese Embassy or Consulate-General if necessary.

Good luck!