is there any bus from shantou to yongding ?

There is no direct long-distance bus between these two places.
You are suggested to take a tain from Chaoshan Railway Station to Guangzhou South Railway Station first. The duration is about 3 hours. After arriving, take subway line 2 to Guangzhou Main Railway Station. There are several normal speed trains that can take you to Yongding directly. The trip takes around 8 hours.