I need to travel from Guilin to Chongqing.
What is the best way to do it
There is one train that goes from Guilin to Chongqing. It leaves around noon time and arrives in Chongqing next morning. Travel time is close to 20 hours, so not a particularly fast train. Should get a sleepthing berth. A hard hard sleeping berth ticket cost about ¥270; a soft sleeping berth, ¥450. A hard seat costs about ¥160, but it is definitly not advised for this trip. There are also soft seats, but they don't help much given the length of the journey. Also it may be difficult to get a train ticket. Normally train tickets are sold 10-14 days in advance. During holiday seasons, tickets are sold 20 days in advance.
The train, K651/654, originates at Guilin North (Guilin Bei) Railway Station, with a stop at Guilin Railway Station before it gets out of the area.
If you fly, flight time is just a little over an hour. There are four or five daily flights between from Guilin Liangjiang Airport and Chongqing Jiangbei Airport, operated by Air China, Southern Airline, Hainan Airline, and Xiamen Airline. If you are not flying during a holiday season, a plane ticket, one-way, costs ¥400-500. Otherwise, it could be in the range of ¥700-1200. There is a wider window for purchasing plane tickets, ranging from a couple of days to months in advance.
This would be too long a trip to go by bus. Road distance between Guilin and Chongqing is approximately 1,300 km.