Two ways in
You can fly from Kathmandu to Lhasa, or cross overland through Gyirong. Both require the Tibet Travel Permit and an arranged itinerary with a group or receiving service.
Via mainland China
Many travellers fly from Kathmandu to Chengdu, Guangzhou or Xi'an first, obtain the permit, then continue to Lhasa by air or by train. Chengdu has the most daily connections; Guangzhou and Xi'an also work well.
Direct Kathmandu–Lhasa flights
Kathmandu is the only foreign city with direct flights to Lhasa; the flight takes about an hour and a half and costs roughly 300 US dollars one way. Two flights normally operate — confirm the day's schedule in advance.
Overland via Gyirong
The road route from Kathmandu to Lhasa is popular with travellers who want the scenery. You need the permit, a Nepali visa and time for border formalities; allow a spare day for weather or road delays.