My friends say it takes 14 to 16 hours, on an uncomfortable sleeper bus, you have to put up with people smoking, puking, and video playing all the time. Flying or taking the train is a much better deal.
But if you really want to torture yourself, I believe you can buy tickets at the Yin Hu long-distance bus station.
I tried to buy train tickets, they are all sold and the frights are too expencive on the dates I want to go(((
But thnks for warning,