There is no direct train from Gutian County to Hong Kong. By train, you could transfer at Zhuzhou, but which will be detouring. Personally, you could try the transport way below. 1. take the long-distance bus to Shenzhen by costing around 13hrs, and then reach Hong Kong after passing the port; 2. take a bus to Nanping or Fuzhou first and then take the train K638/K635 to Shenzhen. For the fastest way, you could take a bus to Fuzhou first and then take flight to Hong Kong directly.