Hi, if you child is born in China you do the following:
1. Get the birth certificate
2. Do all that is necessary and get the passport for your baby
3. The company that you are employed with should help you apply for a dependent's (also called family) visa/residence permit and it usually done the following way: they "sign" the baby on the work permit (need the birth certificate, baby's passport and 2 passport size photos). After it is done: fill the application form and stamp it with the company's seal; write a letter requesting to grant the dependent's visa, bring the copy of company's official papers (license and such)+ the original, barcode picture +2 pictures blue background; father's passport + copy (front page and visa page); birth ceritificate + copy of it; baby's passport + copy of it. After the documents are reviewed (which takes about 3-4 min) and if everything is order you get your recept which you pay after 5 working days when you get your baby's multiple entry family.
You and the baby don't need to be present there.
If your baby was born abroad and you are coming with the baby for the first time, just come on L visa and it will be changed the same way I described above.
Last but not the least: when the company applies for family visas for the members of the employees family they should inquire about the proceedure from the Immigration office itself. They'll be told everything in details (which exact documents should be submitted etc).