There is no direct transportation supplied from Hong Kong to Changsha or Xiangtan currently. However, you could take a bus or train from Hong Kong to get to Guangzhou firstly. Then, at Guangzhou North Railway Station, you could take the high-speed train (CNY312)to arrive in Changsha in 2.5 hours, or a regular train (CNY177/hard-sleeper) to arrive in Changsha in 8~9 hours.

And, both at Guangzhou Railway Station and Guangzhou North Railway Station, you could take a regular train to get to Xiangtan directly in 9 hours.