what types of documents i have to collect for to get a visa to China? And how many days its took for to get visa?

You can apply for a single entry China tourist visa if for tourism. Following documents are required:
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 China.
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. If visiting family in China, proof of relationship, photocopy of the identity document and residence permit of the relative in China are required.
5. bank statements, round-trip air tickets booking, etc.
General processing takes 4 working days from the embassy/consulate.

Thank you for the reply. I don't have any specieal invitation but recommendation letter from my office i can provide. Another things, how many months bank detials needed for to get the visa?

At least 3 months bank statement with adequate money is required.