There is no direct train or bus from Changsha to Lushan. If you take a bus, you have take a bus to Jiujiang City first, taking about 18 hours. Then take a bus from Jiujiang city to Lushan Mountain for about 1 hour. If you take a train, you can take a bullet trian from Changsha to Nanchang first, taking about 3 hours. Then transfer to the other train to Lushan for about 1 hour. So I think train is much quicker and comfortable than bus.