The water vapor transports and budgets are analyzed by using the NECEP/NCAR reanalysis data from 1994 and 1998. The results show that the Jianghuai valley was mainly controlled by moisture transport from north to south in drought years and east to west transport in flood years. The water vapor inputs in dry summers from the west and south boundaries were obviously less than those in flood years, which is an important cause for droughts and floods in the Jianghuai valley and should be paid great attention in the drought/flood prediction service.