I need a visa to travil to china to attend a conference

You need to apply for a F type. The required documents include: your passport (with blank pages and valid at least six months before it expires), fully filled application form affixed with a recent passport size photo, an invitation Letter of Duly Authorized Unit" or "Confirmation Letter of Invitation" prescribing the visa validity, number of entries and stay period.

Sometimes, you are required to provide rount trip air tickets and hotel reservation in China and financial proof.