From Guangzhou Railway Station: Walk to the Liuhua Bus Station and take the South Railway Station Direct Bus.
From Baiyun Airport: You can take the Airport Express Bus 1 to the final station--the Guangzhou Railway Station, and then take the direct bus to South Railway Station.

Thank you very much Mr. King .... for your kind information. Would u please inform me how many minutes needed to reach Guangzhou Railway Station from Baiyun Airport ....& from Liuhua Bus Station to South Railway Station ? How would be the bus fare for the both route ?

It takes about 40-60 minutes from the airport to the railway station, depending on the traffic condition. The fare is about 20RMB. It is 30km from Liuhua to South Railway Station. There is special bus Line in Liuhua Station. It takes about 45 minutes.