6-8hrs.there is one bus starting from Xichang at 8:30 directly to Lugu Lake and the tickets will cost you 74 yuan.you`d better take some medicine in case of carsickness,for some parts of the road are not so good.but anyway the sceneries along the way are extremely beautiful.i have heard that there is one more bus line opened up from Xichang to Lijiang directly in 2008and the bus usually stops at Lugu Lake，im not quite sure about it.check it when you are in Xichang.