I need a multiple entry visa to China

You can apply for China tourist visa in Nepal, but a single entry visa is only valid for 3 months from the date of issuance. If you travel to China from Mongolia 3 months later, it expires. It takes 4 working days for visa processing. The requirements are:
1. The original passport with at least six-month validity and two blank visa pages, one photocopy of the passport page containing the personal particulars.

2. Truly completed and signed Visa Application Form of the People's Republic of China. One recent passport-photo size color photograph of the applicant.

3. Invitation letter (if visit for the first time). If the applicant cannot provide an invitation letter, please provide a visa recommendation letter from the applicant's employing company, organization, etc.

4. Other additional documents required according to the merits of each applicant, e.g. bank statements, round-trip air tickets booking, etc.