I am planning to travel from Guangzhou to Dapu and to Guilin.

From the information that I have checked, there is no direct bus or train operating between two places. You need to take a train to Guangzhou East Railway Station first. Then you may take metro line 1 to Gongyuanqian Station and transfer line 2 to the South Railway Station. Afterwards, you can take a train to Guilin.
Besides, you can also charter a car to Guilin directly.

Thanks Mike for your info. Looks like I have to go back to Guangzhou to go Guilin. There is a high speed train from Guangzhou to Guilin, about 3 hrs ride. I may travel there by high speed train.