Using the monthly precipitation data of 39 meteorological stations from 1961 to 2010 in rainy season over Tibetan Plateau and the NCAR/NCEP reanalysis data, the flood and drought distributions are discussed based on the 〖WTBX〗Z〖WTBZ〗 index and regional flood/drought indexes. The composite analysis method is used to analyze water vapor transport differences between flood and drought years over the Tibetan Plateau. The results show that droughts occur much more frequently than floods over the Tibetan Plateau in recent 50 years. The dry and wet conditions have obvious inter decadal variations. Floods and droughts over the Tibetan Plateau are closely linked to water vapor transport anomalies. There are significant differences between typical drought and flood years in the zonal, meridional, and the total water vapor fluxes and water vapor flux divergence over North Indian Ocean, the western North Pacific, and the mid latitude regions of Asian. The difference appears most significantly at the cross equatorial jet area; and the major difference in the zonal water vapor flux is found in the Somali jet area, and that in the meridional water vapor flux is found in in the Philippines jet area.