Passengers will be able to leave Kunming in the morning and arrive at Bangkok at night when a new railway is complete in three years, according to media reports.
The train journey between the Chinese and Thai cities is estimated to cost up to two thirds less than the cost of plane ticket.
It would bring more economic cooperation opportunities and tourism between China and Thailand.
Construction will start by the end of October, with the railway, passing through Laos on its way to Bangkok, to be finished in three years. A round-trip cost from Kunming to Bangkok will be about 700 yuan. In the future, the railway could be extended to Malaysia, Singapore and Indonesia.