By air
Air China, Sichuan Airlines, China Southern Airlines, and China Eastern Airlines all have frequent service to Lhasa. The easiest direct route is from Chengdu, which has as many as 10 daily flights during the summer months for about $200 each way. There are also frequent flights from Beijing, Guangzhou, Xi'an , and Chongqing. If you are coming from Kathmandu, the nonstop flights made three times a week will give you fantastic view of the Himalays. You must show your permit from the Tibet Tourism Bureau when you check in.
By bus
Intercity travel by bus is not only long and uncomfortable, it's also illegal for foreigners in almost all of Tibet. In fact, the only bus generally willing to pick up foreigners is the early morning coach from Lhasa to Shigatse that leaves across from the Kirey Hotel
By car
Travel by car is the only permitted trasporation throughout Tibet for foreigners. Travel agencies can arrange a driver and all of the necessary permits for any destination you can imagine, if you're willing to pay the price. If you're headed to Nepal, make sure you arrange a visa in Lhasa before your departure, as you can never be certain whether or not visas will be issued at the border post near Kodari.
By train The train line to Lhasa, which opened in the summer of 2006, has rewritten many of the world's records for extreme engineering. It's the world highest railway, with more than 366km of track above 13,000 feet, reaching above 16,500 feet in several locations. The line is also home to the world's highest railway station, which at Tangu-la Pass sites at almost 17,000 feet.