The standard approach is from Lijiang, which is the nearest major transport hub. Regular buses from Lijiang bus station to Qiaotou take about 90 minutes and leave in the morning; confirm current schedules at your accommodation in Lijiang. Qiaotou is the trailhead for the high trail and the starting point for most trekkers.
The gorge is naturally combined with the route between Lijiang and Shangrila: buses running between the two pass through Qiaotou and can drop trekkers off. Completing the trek in the Lijiang-to-Shangrila direction (entering at Qiaotou, exiting at Walnut Grove to pick up a bus to Shangrila) is slightly more common, but the reverse is equally viable. There is no train to either trailhead. The entrance fee of ¥45 is collected at the Qiaotou checkpoint. Taxis back from Walnut Grove to Lijiang or to Shangrila can be arranged at the guesthouses at the Walnut Grove end.