From Beijing to Xining, which usually takes 17 hours, there is altitude change gradually from 44 meters to 2,200 meters above sea level. So, passengers will not experience any symptoms of altitude sickness. After Xining, the train will keep running on Qinghai-Tibet Plateau, at an average altitude of above 4,000 meters. When the train moves from Xining to Nagchu, there is an abrupt altitude change from 2,200 meters to 4,500 meters, during which you will also reach the highest point of the rail line - the Tanggula Mountain Pass (5,072 meters). At Nagchu Station, the train will stop for 7 minutes. If you want, you can get out of the train to feel the weather of Tibet Plateau. Moreover, at Golmud Railway Station, the oxygen supply is immediately turned on to compensate for the lack of oxygen in the surroundings. more about： train from beijing to lhasa