I am here at chittagong in Bangladesh.I would like to visit in china. what necessary documents i should submit to get visa?

You have to apply for a tourist visa to China for the visit in China:
The requirements are:
1. Valid passport (at least six months before expiration) with blank visa pages and copy of the first three pages;
2. TYPED Visa Application Form V.2011A with one passport photo.
3. Applicants who have never been to China before should submit in person.
4. Invitation letters in Chinese language by individual/entity in China and six-month bank statement

It takes 4 working days for visa processing.