How can I renew my Indian passport in China? What are the documents needed?

Anand, you can go to Indian Embassy in China to apply for a reissue of the passport. The address of Indian Embassy is:
No. 5, Liang Ma Qiao Bei Jie,
Chaoyang District, Beijing, China

Following papers are required: application form EAP-I which can be downloaded from the embassy's website, your current passport and additional booklets (if any), four recent color passport size photos (with white background), photocopies of the first page, last page, and the valid resident permit/visa page.

If you live in or near Shanghai or Guangzhou, you can also consult with the embassy whether the consulates there can offer passport services by dialing +86-10-8531 2500/2501/2502/2503.