Bus from Guangzhou to Jingdezhen (Jiangxi)

Yes, there are.
You can take the direct long-distance bus at the local Yuexiu South Bus Station or City Bus Station. Only one bus is on schedule every day in each of the two bus station. Bus at the former station leaves at 13:15 and costs CNY260 and that departs from the latter one at 17:05 and costs CNY300.