Beijing south station to airport ? Best way

the best way is to take the airport shuttle bus line 10 from the public transportation hub at the north exit of the south railway station. the bus will stop at Terminal 2, Terminal 1, and finally terminal 3. you should first make sure which terminal building will your flight depart from.
it takes about 1 hour (could be as long as 1.5 - 2 hours if there is traffic jam) and costs CNY 24 per person.