Arrive into T2 on Delta from USA then I depart out of T2 on South China airline at Beijing Airport.

You will transfer from International to International within T2, right? If yes, you may follow this: Flight Arrival- Transfer Procedures- Immigration Inspection- Security Check- Customs Inspection- Wait for boarding.
In addition, you need to go through security check then. You are advised to go through these procedures as soon as possible so that you can catch the next flight.