From Hong Kong airport to bullet train in Guangzhou

You mean you want to take the bullet train from GZ East Railway Station to other cities of China or want to take the bullet train from HK to GZ East Railway Station?
No matter which do you mean, I think you may need to reach GZ East Railway Station, right?
If so, you can take the airport shuttle bus line A21 to reach its terminal at Hung Hom Station. Then you can go to the Hung Hom Station to find the direct train from HK to reach GZ East Railway Station.

Hi Gordon

We want to go to GZ by bullet train (for the experience). We arrive at Hong Kong airport from South Africa and want to go to GZ by bullet train. Or when we leave GZ back to Hong Kong we can go back via bullet train.