What is the best way to travel from Bangkok Thailand to Dunhuang Gansu China?

You can fly to Xian and then take the train K591 to reach Dunhuang directly. Although taking train costs a long time, you can enjoy the scenery along the rails. For booking the train ticket, it is suggested to book in advance and a soft sleeper is recommended.

Or you can choose to fly from Xian to DH in about two hour and twenty minutes.