You need to submit your application to Chinese embassy there in your country, The requirements are as follows:
1. One completed visa application form;
2. One recent passport sized photo;
3. A valid original passport with blank pages.
4. Travel information including the booking of airline ticket and itinerary in China.
5. an invitation letter from your daughter, and her passport number, and your relationship certificate.

Thank you for your reply. Can you please clarify what are the documents you require to certify the relationship. Is it mother and father's birth certificate is not enough? Thanks

The Birth Certificate is Ok to prove the relationship between you, your son and your daughter