Does this round-trip through train mean that 140 includes going from Guiyang to Zhijin Cave and Zhijin Cave back to Guiyang?

The round-trip through train should include the round-trip fare. If you are not at ease, you can contact the supplier to confirm.

Please refer to the pictures taken in July 2022

The prices given by different travel agencies are different, so it is not sure whether the 140 mentioned here includes the round-trip. It is recommended to confirm directly with the travel agency of choice.